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Position Paper: Testing for Mast Cell Activation Disorders and Mast Cell Activation Syndrome

This document has been developed by ASCIA, the peak professional body of clinical immunology/allergy specialists in Australia and New Zealand. ASCIA information is based on published literature and expert review, is not influenced by commercial organisations and is not intended to replace medical advice. Patient/carer support organisations are listed at  www.allergy.org.au/patients/patient-support-organisations.

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Key points

  • Mast cell activation syndrome (MCAS) can be defined as a heterogenous group of disorders presenting with episodic symptoms involving multiple systems that are attributable to mast cell mediator release (e.g. flushing, pruritis, wheeze, gastrointestinal symptoms).
  • The definition and criteria for MCAS have evolved over time, and there are established diagnostic criteria for MCAS.
  • Many patients may have symptoms seen in MCAS but do not meet criteria for MCAS.
  • Diagnosis of MCAS based on consensus criteria requires clinical assessment in conjunction with laboratory assessments, of which tryptase is the most accessible test within Australia. Other laboratory tests are inferior in sensitivity and specificity, without cutoffs established for diagnosis in MCAS.
  • When a diagnosis of MCAS is being considered it is important to ensure differential diagnoses with overlapping clinical features have been investigated. If a patient meets criteria for anaphylaxis this should be managed as per usual standard of care.

1. Background - mast cells

Mast cells are long-living innate immune cells of myeloid lineage that reside within the connective tissues.1 Although most well recognised for their key role in IgE-mediated immediate allergic responses, mast cells are also involved in tissue inflammation and repair, vascular homeostasis and host defense against various pathogens including parasites and bacteria.1 They originate from haematopoietic stem cells of the bone marrow, and mature into mast cells under influence of c-kit ligand and stem cell factor.1

Mast cells contain various mediators within cytoplasmic granules that are released upon activation. Mediators include tryptase, histamine, heparin, prostaglandins, proteases and various cytokines, which have varied effects on different organs.1, 2 Release of mediators results in typical effects well recognised in IgE-mediated immediate allergic reactions such increased vascular permeability, pruritis, increased mucous production leading to airway constriction and congestion, cutaneous urticaria and angioedema, and gastrointestinal upset.1, 3, 4

Mast cells can be activated by both IgE-mediated and non-IgE mediated mechanisms. The classic mechanism is via antigen that crosslinks IgE antibodies bound to high-affinity FceRI receptors on mast cells. Once crosslinking occurs, downstream signalling occurs that ultimately results in degranulation.1, 3 Mast cells are also activated via non-IgE mediated mechanisms including via IgG, complement, microbial components, drugs, toxins, hormones, physical and emotional stimuli, hormones and cytokines.2, 5

Pathologic activation of mast cells can occur in two key settings: (1) Increased numbers or increased function in the absence of usual triggers; or (2) activation and release of mediators out of proportion to a stimulus e.g. infections, venom, allergens.3 Anaphylaxis is included in this latter example.3

2. Mast cell activation disorders

The terminology and nomenclature regarding mast cell activation disorders can lead to confusion.

  • Mast cell activation (MCA) – release of mediators from mast cells due to activation; whereby activation can be local (e.g. urticaria, atopic dermatitis, asthma) or systemic (e.g. anaphylaxis) with varying severity.5 Markers of activation such as mast cell tryptase (tryptase) increase in level during an activation event.5
  • Mast cell activation disorders (MCAD) – an umbrella term describing a group of disorders where mast cell activation occurs. Includes mast cell activation syndrome.
  • Mast cell activation syndrome (MCAS) – a syndrome defined by specific criteria, where there is a history of systemic severe and recurrent mast cell activation with evidence of mast cell mediator release and response to medications directed at mast cell mediators and their effects.5 MCAS is an MCAD where all MCAS criteria all fulfilled.5

Mast cell activation disorders can be classified as primary, secondary or idiopathic in aetiology (see Table 1).

Primary mast cell activation disorders are a heterogenous group of disorders due to defective mast cell progenitors, resulting in clonally increased numbers or increased function of mast cells.3, 6 Symptoms in patients with primary MCAD relate to effects of the mediators and include flushing, hypotension, gastrointestinal cramping, vomiting, diarrhoea and tachycardia.3 Contrasting with secondary MCAD, chronic urticaria and angioedema are not common in primary MCAD (including systemic mastocytosis)3.

Secondary mast cell activation disorder patients have normal mast cell progenitors, and usually mast cell numbers are normal.3 However they are activated to due to micro-environmental triggers,6 or in other words, the population of mast cells is “hyperresponsive”.2 In these diseases mast cells are recruited through a non-mast cell dependent, extrinsic mechanism.2 Examples of secondary mast cell activation disorders include allergic disorders (e.g. IgE or non-IgE mediated), physical urticarias and chronic autoimmune urticaria.2 Symptoms may be sporadic or chronic.2

Idiopathic mast cell activation disorder occurs where there is no identifiable cause.6 This can manifest as anaphylaxis, angioedema, urticaria or mast cell activation syndrome. This diagnosis should be considered when there is recurrent anaphylaxis with no identifiable clonal or mast cell aetiology.2

Table 1 – Classification of mast cell disorders 4, 7

Primary mast cell disorders (increased numbers of identical mast cells [clones], or increased internal signalling of mast cells)

  • Cutaneous mastocytosis
    • More common in children, with more than 90% of cases resolving by adolescence.3
  • Systemic mastocytosis
    • Associated with gain-of-function mutations in proto-oncogene c-KIT, which has a role in proliferation and differentiation of mast cells.3 KIT D816V is detected in >90% of all cases,8 but other mutations may be implicated
  • Mastocytoma
  •  Mast cell leukaemia
  • Monoclonal mast cell activation syndromes (MMAS)
    • Present with symptoms of mast cell activation and lack cutaneous findings. Have either the KIT D816V mutation or CD25+ mast cells in their bone marrow.3
    • Meet one or two minor diagnostic criteria for mastocytosis, but do not meet full criteria.9 

Secondary mast cell disorders

(normal mast cells and normal numbers, but “hyper-responsive” to external stimuli; have a condition that can induce mast cell activation)

  • IgE-mediated hypersensitivity reactions
    • E.g. food, insect, drug-induced
  • IgE-independent reactions (other receptors/pathways involved)
    • E.g. vancomycin, opioids
  • Mast cell hyperplasia
    • Associated with neoplasia, autoimmune conditions, chronic infections

Idiopathic

(no identifiable clonal or underlying mast cell pathology)

  • Includes idiopathic anaphylaxis
  • Includes mast cell activation syndrome (a syndrome defined by specific criteria)

3. Mast cell activation syndrome (MCAS)

Mast cell activation syndrome (MCAS) has been defined as a heterogenous group of disorders of varied causes that present with episodic symptoms involving multiple systems that are attributable to mast cell mediator release.3 There is no single symptom that is considered specific for mast cell activation syndrome.3 

An internationally endorsed position paper including definitions for MCAS was published in 2012 (see below).4 It is agreed that MCAS should be considered a diagnosis of exclusion.6, 7, 10 Therefore for a diagnosis of MCAS, the diagnostic criteria for primary, secondary, and other well-defined idiopathic mast cell activation disorders (MCAD) must be ruled out first, and in addition the criteria for MCAS must be met.5, 7

A common clinical scenario is that patients with varied chronic rather than episodic symptoms involving multiple organ systems with no clear unifying cause are referred on for investigation of MCAS.

Symptoms of concern may include flushing, unexplained hypotension and fluctuations in blood pressure, itching, chronic fatigue, fibromyalgia-like pain, headache, various types of rashes, intolerances to foods, medications and environmental triggers, and neuropsychiatric features.2, 3, 10, 11

In recent years patients presenting with such symptoms with no other clear cause identified after extensive review have increasingly been labelled with so called “MCAS”,2 without meeting the consensus criteria for MCAS which will be discussed below. Incorrectly diagnosed patients may then receive unnecessary treatments or inappropriate treatment, or may not receive treatment for other medical conditions that may present with similar clinical features.11

Additionally, patients with some forms of Ehlers-Danlos syndrome and postural orthostatic tachycardia syndrome (POTS), may describe features that overlap with those of mast cell activation (e.g. flushing and gastrointestinal symptoms).3, 6, 11 There is currently no scientific evidence that these conditions are associated with dysregulated mast cells and chronic mast cell mediator release, and these conditions should not be used as part of the criteria to diagnose MCAS.3, 11, 12

Differential diagnoses for MCAS

Of importance, there is considerable overlap between symptoms occurring in MCAS and various other clinical entities. For example flushing can occur in various neuroendocrine or neoplastic conditions such as carcinoid syndrome, medullary thyroid cancer, renal cell carcinoma and phaeocromocytoma.10 Other conditions with similar symptoms to those in MCAS include testosterone or estrogen deficiency, inflammatory bowel disease and allergic reactions.2

It is therefore essential that tailored workup based on clinical assessment has been appropriately performed rule out these other differentials. Some examples are provided below in Table 2, but additional discussion is beyond the scope of this paper. Further detail can be obtained from an excellent review by Picard et al (2013). 

Table 2 – Examples of differentials and investigations for mast cell activation disorders (adapted from Picard et al)7, 13

Differential

Relevant signs and symptoms

Tests

Carcinoid syndrome

Flushing, diarrhoea, wheeze

  • Plasma 5-hydroxyindoleatic acid (HIAA)
  • 24-hour urinary HIAA 

Phaeochromocytoma

 

Flushing, hypertension, tachycardia

  • Plasma metanephrines  
  • 24 hr Urinary metanephrines and catecholamines  

Menopause

Flushing

  • FSH, LH, oestrogen

Medullary carcinoma of thyroid

Flushing

  • Serum calcitonin

Cardiac arrhythmias

Tachycardia, presyncope/syncope, hypotension

  • ECG

Postural tachycardia syndrome

Tachycardia, presyncope/syncope, hypotension

  • Tilt table test

Asthma

Wheeze

  • Pulmonary function tests

Vocal cord dysfunction

Wheeze, stridor

  • Laryngoscopy, spirometry

Hereditary angioedema

Angioedema, throat tightness

  • C4 +/- C1 inhibitor levels and/or function

Primary bowel disease (e.g. irritable bowel syndrome, inflammatory bowel disease)

Diarrhoea

  • Endoscopy with biopsy

Neuroendocrine tumours

May include flushing

  • Serum vasoactive intestinal peptide

Hereditary alpha tryptasemia (HAT) – can co-exist with MCAS

Flushing, urticaria, pruritis, hypotension, tachycardia, syncope/presyncope, gastrointestinal symptoms

  • Baseline mast cell tryptase
  • Increased TPSAB1 gene copy number

MCAS and hereditary ∝ tryptasemia

A proportion of patients diagnosed with MCAS may have a co-existing recently described genetic trait hereditary alpha tryptasemia (HAT)3. Patient with HAT have an increased copy number of the gene TPSAB1 on a single allele – the gene encoding alpha-tryptase.14 Confirmation of HAT is performed by genetic testing generally requested via tertiary centres. The clinical phenotype for HAT is still being elucidated, though common features include systemic reactions to stinging insects, respiratory wheeze, atopy, skin flushing and itching, symptoms of autonomic dysfunction, and inflammatory bowel syndrome-like abdominal symptoms.5, 14, 15 HAT patients typically have a basal serum tryptase > 8 ng/ml,16 which notably is below the common cutoff of 11.4 ng/ml used in labs within Australia.

Although the exact interplay between HAT and MCAS is uncertain, it has been hypothesised that HAT may be a risk factor for MCAS, though the clinical phenotype for HAT appears broader than that described for MCAS.13 It has been suggested that those with MCAS should be investigated for HAT,13 and HAT has been linked to elevated risk to develop anaphylaxis and MCAS.5 More research is needed in this area.

4. Diagnosis of MCAS

Diagnostic criteria

The definitions and criteria for diagnosis of mast cell activation disorders and mast cell activation syndrome have evolved over time. The key considerations to make a diagnosis of MCAS include severe, recurrent symptoms of mast cell activation (typically anaphylaxis), along with confirmation of mast cell lineage involvement via detection of mast cell mediators.5 

In an attempt to provide a consensus on the diagnosis criteria for MCAS, an international consensus group (Valent et. al 2012) proposed the following criteria, where all three criteria should be fulfilled for MCAS to be diagnosed.17 The criteria have since been validated in various studies.5

  • Typical signs and symptoms of mast cell mediator release (affecting at least 2 organ systems)
    • Skin: flushing, pruritus, urticaria, angioedema
    • Cardiovascular: hypotension
    • Respiratory: wheezing, throat swelling
    • GI: diarrhea
    • Naso-ocular: pruritus
  • Objective evidence of mediator release
    • Elevated serum tryptase: 20% + 2 ng/mL above baseline
    • Elevated 24-hour urinary histamine metabolites (methylhistamine)
    • Elevated 24-hour urinary prostaglandins (prostaglandin D2; 11b platelet-derived growth factor 2a )
  • Response to therapy that blocks mast cell mediator activity
    • H1-receptor with or without H2-blockers, ketotifen, cromolyn sodium, aspirin, and leukotriene receptor antagonists 

The role of laboratory testing in MCAS

As previously mentioned, various mediators are produced and released by mast cells when activated. Various mediators can be detected in serum or urine and thus used as biomarkers for mast cell activation.5 Such markers vary in sensitivity and specificity for mast cell activation.5 Unfortunately, non-validated laboratory tests have been used in some cases to make a diagnosis of MCAS which can cause confusion for both patients and clinicians.11

Mast cell tryptase (trypase) remains the marker of choice for laboratory investigation of MCAS as per international consensus.4 This is due to issues with sensitivity, specificity and established reference ranges for other markers of mast cell activation such as urinary metabolites of histamine, blood prostaglandin D2 and metabolite 11-b-prostaglandin F2a, and urinary leukotriene E4.4

Markers of mast cell activation are discussed in further detail in Table 3 below.

Importantly, reference ranges for mediators other than tryptase have not been established for mast cell activation,3 and other laboratory tests that not mentioned in Table 3 have not been validated nor recommended for diagnosis of MCAS.

As per consensus guidelines, evidence of mediator release via elevated 24-hour urinary histamine metabolites or elevated 24-hour urinary prostaglandins can also be requested4 but can be more difficult to perform, and subject to specific pre-collection requirements that may affect sensitivity of the assays. Cutoffs for diagnosis of MCAS have also not been established.

A rise in tryptase level occurs following mast cell activation, peaking within 4 hours and returning to normal levels by 24 hours. Therefore ideally, tryptase should be measured:

  • Within 15 min to 4 hours of the event
  • A baseline measurement for comparison is required at least 24 hours after the event to ensure a subsequent fall to normal levels.7
  • Criteria of an elevation in tryptase least 20% + 2ng/mL over baseline is considered indicative of mast cell activation as per the aforementioned consensus guidelines.4

Unfortunately, the majority of patients describing symptoms relating to potential MCAS have either slight elevations in tryptase not considered a significant change from baseline, or no increase from their baseline - hence not meeting criteria for MCAS.5 Therefore, in such cases a diagnosis of MCAS cannot be made.5

To summarise, the majority of laboratory markers of mast cell activation that have been described in the literature are either not recommended, or not readily available for assessment in clinical laboratories within Australia. 

Table 3: Markers of mast cell activation

Marker

 

Serum mast cell tryptase (tryptase)

  • Marker of choice as per international consensus4
  • Specific marker of mast cell activation and/or mast cell burden3
  • Levels more than 11.4ug/L are considered increased.
  • Criteria of at least 20% + 2ng/mL over baseline is considered indicative of mast cell activation.4
  • Can also be increased due to other reasons e.g. renal failure, hereditary a tryptasemia and clonal mast cell disorders e.g. systemic mastocytosis

Urinary metabolites of histamine (e.g. N-methyl histamine and 1-methyl-4-imidazole acetic acid)

  • 24-hour collection recommended
  • Relatively specific for mast cell activation3
  • Cutoffs for MCAS not established

Blood histamine levels

  • Histamine lacks sensitivity and specificity4
  • May be derived from basophils at baseline rather than mast cells3, 4
  • Can have spuriously elevated results relating to storage and collection3
  • Cutoffs for MCAS not established

Urinary histamine levels

  • Histamine lacks sensitivity and specificity4
  • Can be affected by microbial contamination; as well as diet and sample storage3
  • Cutoffs for MCAS not established

Blood prostaglandin D2 and metabolite 11-b-prostaglandin F2

  • PGD2 lacks sensitivity but is not produced by basophils4
  • Marker of mast cell activation but not specific; also produced by eosinophils and non-immune cells
  • Cutoffs for MCAS not established

Urinary leukotriene E4 (metabolite of leukotriene C4, lipid mediator)

  • Not well correlated with mast cell activation symptoms
  • Cutoffs for MCAS not established

Chromogranin A

  • Resides in neuroendocrine cells, not derived from mast cells11

Heparin

  • Not validated as serum marker of mast cell activation11

5. Management of MCAS

Management of MCAS varies depending on the underlying cause. For suspected primary MCAS, referral to Clinical Immunologists and Haematologists may be required for additional investigations such as a bone marrow biopsy to confirm or rule out a clonal disorder.

A detailed discussion of management of MCAS is beyond the scope of this paper, but in general the approach to management will include:

  • Identification and avoidance of triggers (allergens, physical etc.)
    • This can be facilitated by Immunological assessment to confirm history and to facilitate further investigations if indicated (e.g. skin prick testing, specific IgE testing if IgE-mediated reaction suspected).
    • This includes appropriate management of anaphylaxis with adrenaline autoinjector training and Anaphylaxis Action Plan if indicated.
  • Pharmacological management targeting mast cell mediators  
    • Pharmacological management is an important part of management of MCAS and patients with this syndrome should be able to demonstrate improvement and response to medications targeting mast cell mediators.3
    • This is usually trialled in a stepwise fashion under specialist guidance, and some medications can be targeted to particular systems involved.
    • Medications that can be utilised include3, 7:
      • H1 histamine receptor antagonists (e.g. cetirizine, loratadine, fexofenadine – non-sedating second generation agents preferred)
      • H2 histamine receptor antagonists (e.g. nizatidine, famotidine)
      • Anti-leukotriene medications (e.g. Montelukast)
      • Mast cell stabilisers (e.g. cromolyn sodium, ketotifen)

There are no evidence-based dietary modifications recommended for patients with MCAS.18 Current consensus guidelines do not suggest any dietary modifications for MCAS.

It is not uncommon for patients to have trialled a low Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols (FODMAP) diet or a low histamine diet.18 Such diets are commonly encouraged via social media platforms or lay literature online,18 but there are no sufficiently well designed clinical trials or biomarkers available to assess the efficacy of such diets in MCAS. It is important to ensure patient diets are well-balanced and not excessively nutritionally restrictive, and in the setting of dietary modifications seeking input from a dietician experienced in food intolerances is recommended.

© ASCIA 2024

Content developed February  2024

For more information go to www.allergy.org.au/anaphylaxis

To support allergy and immunology research go to www.allergyimmunology.org.au/donate

References

  1. Krystel-Whittemore M, Dileepan KN, Wood JG. Mast cell: a multi-functional master cell. Frontiers in immunology. 2016: 620.
  2. Akin C, Valent P, Metcalfe DD. Mast cell activation syndrome: Proposed diagnostic criteria. The Journal of allergy and clinical immunology. 2010; 126: 1099-104.e4.
  3. Akin C. Mast cell activation syndromes. Journal of Allergy and Clinical Immunology. 2017; 140: 349-55.
  4. Valent P, Akin C, Arock M, Brockow K, Butterfield JH, Carter MC, et al. Definitions, criteria and global classification of mast cell disorders with special reference to mast cell activation syndromes: a consensus proposal. International archives of allergy and immunology. 2012; 157: 215-25.
  5. Valent P, Hartmann K, Bonadonna P, Niedoszytko M, Triggiani M, Arock M, et al. Mast cell activation syndromes: Collegium Internationale Allergologicum update 2022. International Archives of Allergy and Immunology. 2022; 183: 693-705.
  6. Frieri M. Mast Cell Activation Syndrome. Clin Rev Allergy Immunol. 2018; 54: 353-65.
  7. Picard M, Giavina-Bianchi P, Mezzano V, Castells M. Expanding spectrum of mast cell activation disorders: monoclonal and idiopathic mast cell activation syndromes. Clin Ther. 2013; 35: 548-62.
  8. Scherber RM, Borate U. How we diagnose and treat systemic mastocytosis in adults. British journal of haematology. 2018; 180: 11-23.
  9. Valent P, Akin C, Escribano L, Födinger M, Hartmann K, Brockow K, et al. Standards and standardization in mastocytosis: consensus statements on diagnostics, treatment recommendations and response criteria. Eur J Clin Invest. 2007; 37: 435-53.
  10. Lafont E, Sokol H, Sarre-Annweiler M-E, Lecornet-Sokol E, Barete S, Hermine O, et al. Étiologies et orientation diagnostique devant un flush. La Revue de médecine interne. 2014; 35: 303-09.
  11. Weiler CR, Austen KF, Akin C, Barkoff MS, Bernstein JA, Bonadonna P, et al. AAAAI Mast Cell Disorders Committee Work Group Report: mast cell activation syndrome (MCAS) diagnosis and management. Journal of Allergy and Clinical Immunology. 2019; 144: 883-96.
  12. Jackson CW, Pratt CM, Rupprecht CP, Pattanaik D, Krishnaswamy G. Mastocytosis and mast cell activation disorders: clearing the air. International Journal of Molecular Sciences. 2021; 22: 11270.
  13. Kranyak A, Shuler M, Lee LW. Cutaneous Manifestations in Hereditary Alpha Tryptasemia. Cutis. 2023; 111: 49-52.
  14. Lyons JJ, Yu X, Hughes JD, Le QT, Jamil A, Bai Y, et al. Elevated basal serum tryptase identifies a multisystem disorder associated with increased TPSAB1 copy number. Nature genetics. 2016; 48: 1564-69.
  15. Robey RC, Wilcock A, Bonin H, Beaman G, Myers B, Grattan C, et al. Hereditary alpha-tryptasemia: UK prevalence and variability in disease expression. The Journal of Allergy and Clinical Immunology: In Practice. 2020; 8: 3549-56.
  16. Lyons JJ. Hereditary alpha tryptasemia: genotyping and associated clinical features. Immunology and Allergy Clinics. 2018; 38: 483-95.
  17. Valent P, Akin C, Arock M, Brockow K, Butterfield JH, Carter MC, et al. Definitions, criteria and global classification of mast cell disorders with special reference to mast cell activation syndromes: a consensus proposal. Int Arch Allergy Immunol. 2012; 157: 215-25.
  18. Hamilton MJ, Scarlata K. Mast Cell Activation Syndrome-What it Is and Isn’t. Pract Gastroenterol. 2020; 44: 26-32.

ASCIA Newborn Screening for Severe Combined Immune Deficiency (SCID) and BCG Vaccination Position Statement

This document has been developed by ASCIA, the peak professional body of clinical immunology/allergy specialists in Australia and New Zealand. ASCIA information is based on published literature and expert review, is not influenced by commercial organisations and is not intended to replace medical advice.         

For patient or carer support contact AusPIPSHAE AustralasiaIDFA, or IDFNZ.

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The Bacille Calmette–Guérin (BCG) vaccine is primarily used to prevent tuberculosis (TB) infection and disease in regions and population groups with high TB incidence in In Australia and New Zealand.

There are differences in epidemiology of TB infection across Australia and New Zealand, with recent high burden of infection in some Australian regions, and differences in routine BCG vaccination practices for at-risk neonates.

In the ideal setting (as recommended in the UK), newborn screening results for severe combined immune deficiency (SCID) would be reviewed prior to administration of BCG vaccines and withheld in the case of an abnormal screening result. However, this is not practical, and could lead to delays or missed opportunities, if BCG vaccines are not administered prior to the neonate being discharged home, before newborn screening test results are available.

Overall, the risk of SCID is very small (around 1 in 60,000 infants born in Australia and New Zealand), whereas the risk of TB infection in some regions and population groups is much higher.  

Infants with SCID have absent or low numbers of T lymphocytes (T cells) and therefore a high risk of infections. Newborn screening for SCID allows these infants to be diagnosed and treated early, which improves long term outcomes and enables early life saving treatment with bone marrow transplantation. Transplantation can cure SCID if performed early, before infants have life-threatening infections.

Currently there is no international consensus regarding BCG vaccination in the context of newborn screening for SCID, and there is limited available data/literature.

Therefore, the following recommendations are based on expert experience and consensus:

  • At-risk neonates should continue to receive BCG vaccination prior to discharge in the immediate antenatal period. There are risks of reduced BCG vaccine uptake and coverage if vaccination is delayed or omitted, with implications for public health and disease control.
  • Parents of infants who are receiving BCG vaccination should be counselled regarding the risk/benefit profile of BCG vaccines. This should be provided prior to the results of newborn screening tests being available, and reinforced with an information sheet.

© ASCIA 2024

Content developed January 2024

For more information go to www.allergy.org.au/hp/papers/immunodeficiency

To support allergy and immunology research go to www.allergyimmunology.org.au/donate

Page created 11 January 2024

Position Paper: Laboratory Tests for Autoimmune Diseases

This document has been developed by ASCIA, the peak professional body of clinical immunology/allergy specialists in Australia and New Zealand. ASCIA information is based on published literature and expert review, is not influenced by commercial organisations and is not intended to replace medical advice. Patient and carer support organisations are listed at www.allergy.org.au/patients/patient-support-organisations.

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Overview of tests for autoimmune diseases

A diagnosis of autoimmune diseases is obtained by using a combination of:

  • Detailed clinical history,
  • Physical examination, and
  • Other investigations, including laboratory testing, such as serological (antibody) tests, tests for acute phase reactants and in some cases, biopsies for histological confirmation of disease.

Laboratory test results do not usually have adequate predictive value to be diagnostic unless they are used in conjunction with the patient’s clinical history and physical examination.

Therefore, they should not be used as screening tests in unselected populations.

Consensus diagnostic and/or classification criteria for autoimmune diseases have been developed for target populations and incorporate a range of findings, including clinical history, physical examination and serological test results.

Autoantibodies are markers of autoimmune diseases

Autoimmune diseases are due to a breakdown in the body’s self-tolerance, either central or peripheral. This results in the immune system targeting self-peptides, leading to tissue damage or destruction.

Autoimmune diseases can be antibody mediated or immune cell mediated and are classified as systemic or organ specific.

Autoantibodies are referred to as markers of autoimmune disease, but they do not cause autoimmune diseases. Autoantibodies can be directly involved in the pathology of antibody mediated autoimmune diseases or they can be associated with autoimmune diseases.

Laboratory tests for autoimmune diseases

The laboratory can assist with diagnosis confirmation of autoimmune diseases by performing:

  • Primary tests to identify autoantibodies or disease markers in patients with clinical features that are suggestive of autoimmune disease.
  • Secondary tests for further autoantibody characterisation, diagnosis, prognosis or monitoring autoimmune disease activity.

Laboratory tests are also used in management of autoimmune diseases (particularly when they are antibody mediated) to predict flares, monitor efficacy of therapy and monitor disease progression.

Serial monitoring of autoimmune diseases is limited to a smaller number of tests which have been shown to fluctuate with disease status.

Types of laboratory tests

Multiple methods are used in the laboratory to detect the presence of autoantibodies, with descriptive and semi-quantitative or quantitative results.

Descriptive and semi-quantitative assays include:

  • Indirect immunofluorescence assays (IFA) to measure tissue autoantibodies, antinuclear antibodies (ANA), anti-neutrophil cytoplasmic antibodies (ANCA).
  • Immunoblot (line) assays, such as antibodies to extractable nuclear antigens (ENA).
  • Cell based assays for autoantigens expressed on cells engineered to express antigens otherwise difficult to detect (such as aquaporin-4, CASPR-2, DPPX, NMDA receptor, AMPA receptor, desmoglein-1, desmoglein-3 autoantibodies).

Depending on the diagnostic query and the pattern of immunofluorescence observed, positive ANA tests should be followed up by assays to determine the type of ANA present.

Autoantibodies recognising one or more of these nuclear antigens can also be individually assessed (antibodies to ENA or double stranded [ds] DNA). Antibodies to these individual nuclear components can have specific disease associations or prognostic value.

Quantitative assays include:

  • Enzyme linked immunosorbent assays (ELISA) and assays which are based on a similar principle, including fluorescence enzymes (FEIA), and chemiluminescence (CLIA).
  • Addressable laser bead immunoassays (ALBIA) which is a multiplex technology that can assess several antibody specificities simultaneously on a small serum sample volume.
  • Radioimmunoassays (RIA).

Quantitative assays can detect specific immunoglobulin isotypes or all bound immunoglobulin. However, in most cases the assays are not standardised and numerical results cannot be directly compared between methods and different laboratories.

Clinicians should be mindful of variation between different test methods and laboratories, and what is defined as a clinically relevant change in the result for the autoantibody. Therefore, it is important that the same quantitative test method and laboratory is used for monitoring of a patient’s autoimmune disease.

In a quantitative assay, the autoantigen is presented on either a tissue, as a molecule in solution or bound to a solid phase such as a membrane or polystyrene well. Patient serum is incubated with the antigen allowing the antigen specific antibody to bind to the substrate.

Following a washing step bound patient serum is detected using an anti-human immunoglobulin antibody labelled with a fluorescent tag or enzyme which allows quantitation and/or visualisation of the bound autoantibody. Alternatively, the antigen antibody complex may be immunoprecipitated and quantified.

Biopsy testing in autoimmunity

The deposition of immunoglobulin or complement components seen in skin and renal biopsies can also be used to inform the clinicians about the pathogenic mechanisms involved and which disease is present.

This involves a direct immunofluorescence staining method when using fresh frozen tissue and is reported qualitatively.

In some cases the degree of staining may be scored as a percentage of tissue affected in the biopsy.

Prevalence of some autoantibodies associated with autoimmune diseases

Advances in laboratory technology, reagents, alternative assay methods and expanding understanding autoimmune diseases have shown that many patients with no autoimmune diseases have a detectable autoantibody. An example of this is anti-nuclear antibodies (ANA) which occur with variable frequency in almost all autoimmune diseases, and in the context of neoplasia. They are also found in a small proportion of healthy subjects, usually in low titer, and frequency of detection increases with age.

Certain antibodies can be detected many years before clinical presentation of autoimmune diseases, such as centromere antibodies in limited scleroderma. Several international studies have reported prevalence of serum autoantibodies in their corresponding general population. Ethnicity, gender, age and geographical location may influence the prevalence of autoimmunity.

Turnaround times for autoantibody testing

Turnaround times for autoantibody testing can range from several hours to weeks. However, there are situations when identification and/or quantitation of the autoantibody warrants obtaining an urgent result.

For example, this may require phoning the laboratory if a patient presents with a rapidly evolving disease involving organ failure which may mimic other conditions or emergencies, including vasculitis, Goodpasture Disease and autoimmune encephalitis.

Types of autoimmune diseases

Localised (organ specific) autoimmune diseases mainly affect a single organ or tissue, although the effects frequently extend to other body systems and organs. These diseases are often managed by organ-specific medical specialists, such as endocrinologists, gastroenterologists, neurologists or rheumatologists.

Systemic autoimmune diseases can affect many body organs and tissues at the same time. They can be broadly classified into rheumatological disease and vasculitis disorders. These diseases are often managed by clinical immunology/allergy specialists and/or rheumatologists.

Examples of Localised Autoimmune Diseases 

Examples of Systemic Autoimmune Diseases  

Addison’s disease (adrenal)

Antiphospholipid antibody syndromes (blood cells)

Autoimmune hepatitis (liver)

Dermatomyositis (skin, muscles)

Coeliac disease (gastrointestinal tract)

Mixed connective tissue disease

Crohn’s disease (gastrointestinal tract)

Polymyalgia rheumatica (large muscle groups)

Diabetes Mellitis Type 1a (pancreas)

Polymyositis (skin, muscles)

Grave’s disease (thyroid)

Rheumatoid arthritis (joints, less commonly lungs, skin, eyes)

Guillain-Barre syndrome (nervous system)

Scleroderma (skin, intestine, less commonly lungs, kidneys)

Hashimoto’s thyroiditis (thyroid)

Sjögren’s syndrome (salivary glands, tear glands, joints)

Multiple sclerosis (nervous system)

Systemic Lupus Erythematosus (skin, joints, kidneys, heart, brain, red blood cells, other)

Myasthenia gravis (nerves, muscles)

 

Pernicious anaemia (stomach)

 

Primary biliary cholangitis/ cirrhosis (liver)

 

Sclerosing cholangitis (liver)

 

Ulcerative colitis (gastrointestinal tract)

 

Further information

RCPA - Pathology Tests this list is searchable and provides basic information on a wide range of pathology tests across all disciplines, including autoimmunity.

Information about Vasculitis www.anzvasculitis.org/medical-professionals/

ANA Consensus www.anapatterns.org

© ASCIA 2023

Content developed June 2023

For more information go to www.allergy.org.au/patients/autoimmunity

To support allergy and immunology research go to www.allergyimmunology.org.au/donate

ASCIA Food Allergen Challenge Protocols

ASCIA Food Allergen Challenge Protocols have been developed by ASCIA to standardise protocols used by clinical immunology/allergy specialists in Australia and New Zealand.  

It is important to note that food allergen challenges:

  • Are primarily used to determine if positive food allergy tests are associated with current clinical allergy.
  • Should only be undertaken for patients who have been carefully selected by clinical immunology and
    allergy specialists or appropriately qualified and experienced medical practitioners in consultation with
    clinical immunology and allergy specialists*. *The Scope of Practice is available at https://www.allergy.org.au/ascia-reports#s3
  • May provoke an allergic reaction in sensitised individuals and should therefore only be performed under medical
    supervision with immediate access to emergency treatment for anaphylaxis. ASCIA takes no responsibility for
    any adverse outcomes that may occur using these protocols.

ASCIA information is based on published literature and expert review, is not influenced by commercial organisations and is not intended to replace medical advice. 

Protocols 

pdfASCIA_HP_FAC_Protocol_Baked_Muffin_202385.57 KB

pdfASCIA_HP_FAC_Protocol_Cooked_Egg_202399.76 KB

pdfASCIA_HP_FAC_Protocol_Cow's_Milk_2023166.37 KB

pdfASCIA_HP_FAC_Protocol_Dosage_Guide_2023184.32 KB

pdfASCIA_HP_FAC_Protocol_Generic_202394.11 KB

pdfASCIA_HP_FAC_Protocol_Mixed_Tree_Nuts_202390.57 KB

pdfASCIA_HP_FAC_Protocol_Nut_Single_202387.09 KB

pdfASCIA_HP_FAC_Protocol_Peanut_202387.73 KB

pdfASCIA_HP_FAC_Protocol_Soy_Milk_2023129.76 KB

pdfASCIA_HP_FAC_Protocol_Wheat_2023136.37 KB

Supporting documents

pdfASCIA_HP_FAC_Baked_Egg_Muffin_Recipe_2023109.06 KB

pdfASCIA_HP_FAC_Baked_Milk_Muffin_Recipe_2023129.63 KB

pdfASCIA_HP_FAC_Protocol_Nut_Appendix_2023137.87 KB

Further Information   

ASCIA Position Paper - Food Allergen Challenges 

ASCIA Consent Form - Food Allergen Challenges 

Food Allergen Challenges FAQ 

Food Allergy FAQ 

Dietary Guides for Food Allergy - avoidance information for common food allergens 

Recording results 

To record food challenge results in a standardised format the following form may be used. Uniform recording of food challenges using the ASCIA protocols enables pooling of collective information, with the potential to be a valuable research tool.

docForm for Recording Allergen Challenge Results105.5 KB 

Webpage updated June 2023

Guide for Milk Substitutes in Cow’s Milk Allergy

pdfASCIA HP Guide for Milk Substitutes in Cow’s Milk Allergy 2023198.03 KB

This document has been developed by ASCIA, the peak professional body of clinical immunology/allergy specialists in Australia and New Zealand. ASCIA information is based on published literature and expert review, is not influenced by commercial organisations and is not intended to replace medical advice. For patient or carer support contact Allergy & Anaphylaxis Australia or Allergy New Zealand.

Breastfeeding is recommended for the many benefits it brings to both the mother and child. If breastfeeding is not possible, this Guide can assist health professionals in recommending substitute milks when an infant has cow’s milk allergy (CMA). This Guide also provides information about safe, nutritionally equivalent alternatives if a particular specialised formula is not available due to supply issues.

Exclusion of cow’s milk from a breastfeeding mother’s diet is not necessarily required in CMA and should be discussed with a specialist. If undertaken, cow’s milk exclusion should be supervised by a dietitian.

Commercial names and suppliers of specialised infant formula in Australia and New Zealand, and the method for their supply is provided for ease of reference.

Table 1: Abbreviations used in this document

AAF - Amino acid formula

FPIAP - Food Protein Induced Allergic Proctocolitis

CMA – Cow’s milk allergy

FPIES - Food Protein Induced Enterocolitis Syndrome

eHF – Extensively hydrolysed formula

OTC - Available over the counter

EoE – Eosinophilic oesophagitis

PBS – Pharmaceutical Benefits Scheme (AU)

FPE - Food Protein Enteropathy

PSA - Pharmac Special Authority (NZ)

Table 2: Commercially available specialised infant formula suitable for cow's milk allergy (CMA)

Suitable formula
(see table 3 for indications)

Brand names and suppliers

Availability*

Soy based infant formula

  • Alula® Gold Soy (Sanulac)
  • Karicare® Soy (Nutricia)

OTC

Extensively hydrolysed formula (eHF)

  • Aptamil® Allerpro SYNEOTM 1, 2 and 3 (Nutricia) - contains lactose

OTC

Extensively hydrolysed formula (eHF)

  • Alfaré® (Nestlé) TO BE DISCONTINUED IN 2023 (AU)
  • Aptamil® Gold+ Pepti-Junior® (Nutricia)

PBS and PSA listed (prescription required)

Rice protein based formula                       
(see page 2  for further information)
  • Alula® Gold Allergy (Sanulac)**
  • Novalac® Allergy (Aspen Australia)***

OTC

Amino acid based formula (AAF) for infants <12 months of age

  • Neocate® Gold, LCP and SYNEOTM (Nutricia)
  • Elecare® (Abbott)
  • Elecare® LCP (Abbott)
  • Alfamino® (Nestlé)

PBS and PSA listed (prescription required)

 

Amino acid based formula (AAF) for children >12 months of age

  • Neocate® Junior (Nutricia)
  • Neocate® Junior Vanilla (Nutricia)
  • Elecare® Vanilla (Abbott)
  • Alfamino® Junior (Nestlé)
  • Essential Care Jr (Cortex Health)*

PBS and PSA listed (prescription required)

 

* Not currently PSA listed

* PBS and PSA item numbers are listed on http://www.pbs.gov.au andhttps://www.pharmac.govt.nz/

Rice protein based formula

There are two rice protein based formula available in Australia:

  • Alula® Gold Allergy (Sanulac) – whilst there are no product specific studies hypo-allergenicity or growth studies currently available, each batch is tested for milk and soy contamination.
  • Novalac® Allergy (Aspen Australia) - Product specific hypo-allergenicity and growth studies have been undertaken.

Data is limited for use of rice protein based formula in non IgE mediated food allergies.

Infant formula NOT recommended for cow's milk allergy (CMA)

The following types of formula are NOT recommended for infants with CMA:

  • Standard infant formula including anti-regurgitation, lactose free, organic, newborn, and follow on.
  • Goat milk based infant formula.
  • Other mammal milks and formula.
  • A2 formula.

Table 3: Specialised formula and indications in cow's milk allergy (CMA)

Type of Allergy

First choice

Second choice

(if first not tolerated)

Third choice

(if second not tolerated)

Immediate 
(IgE mediated) CMA 
(not anaphylaxis)

  • eHF (<6 months) or
  • Rice protein based formula*

AAF

 
  • Soy formula** (>6 months) or
  • Rice protein based formula*

eHF

AAF

Anaphylaxis

  • AAF or
  • Soy formula** (>6 months) or
  • Rice protein based formula*
   

FPIES

  • eHF (<6 months) or
  • Rice protein based formula*

AAF

 
  • Soy formula (>6 months and already soy-tolerant/after medically supervised soy introduction), or
  • Rice protein based formula*

eHF

AAF

Non IgE mediated CMA
(FPE, FPIAP)

  • eHF (<6 months) 
  • AAF 
  • Rice protein based formula*
 
  • Soy formula** (>6 months and growing well)
  • eHF
  • Rice protein based formula*

AAF

EoE

  • AAF
   

Atopic dermatitis (eczema) alone is not an indication for specialised infant formula.

* Unless allergic to rice.. eHF or AAF is recommended if poor growth and/or multiple non IgE food allergies.

** Unless allergic to soy. Soy is offered as an option for IgE-mediated CMA and anaphylaxis based on expert opinion, and review of the literature which presents very limited evidence of IgE mediated clinical reactions to soy in children with IgE-mediated CMA. (Adapted from Kemp et al.,2008).

Guidance regarding specialised formula substitutes for cow’s milk allergy (CMA)

If an infant’s usual formula is unavailable, use table 3 to select suitable substitutes. The most straightforward approach is to select a product from the same group that the child is already on (e.g. substitute one eHF for another eHF).

Recommendations for a substitute formula should involve a review of factors that led to the initial choice, and any change in clinical history. For example:

  • A thriving child with non-anaphylactic IgE-mediated reactions to cow’s milk formula was established on eHF due to age being less than six months, but is now older than six months, therefore soy formula should be considered.

When AAF for children older than 12 months is required, but is unavailable:

  • A paediatric allergy dietitian should be consulted to assist with modifying the recipe for a substitute AAF.
  • For all formula changes, recipe instructions should be reviewed with the family, as scoop to water ratios can vary substantially.

For children over 12 months using soy as their milk replacement:

  • Calcium fortified soy milk is an appropriate replacement for soy formula, if they are growing well and eating a wide range of family foods.

For children with cow’s milk and soy allergies:

  • Most plant based milk replacement products that are not calcium fortified are too low in protein, fat, and calcium. Therefore, they are not nutritionally adequate for children under two years of age, unless growth and nutrition have been assessed carefully.
  • Children under four years of age only need 400-500 mL of calcium fortified plant based milk replacements a day to meet their calcium requirements. Larger quantities can reduce appetite, nutritional intake, and growth.

Referral of infants and children with CMA to a paediatric allergy dietitian is recommended to assess nutritional needs.

 

© ASCIA 2023

Content updated June 2023

For more information go to www.allergy.org.au/hp/food-allergy

To support allergy and immunology research go to www.allergyimmunology.org.au