Medical Policy

This document addresses selected unproven blood, serum and cellular allergy and toxicity tests. Allergy testing is used to determine if a symptom could be the result of an allergic reaction (involving antibodies and histamine release). The document does not address generally accepted diagnostic tools such as percutaneous (scratch, prick, or puncture) tests, the allergen-specific serum IgE test, food elimination diets and oral food challenges (double-blind, placebo-controlled food challenge).

For additional information, please see:

• MED.00059 Idiopathic Environmental Illness (IEI)

Investigational and Not Medically Necessary:

The following blood, serum and cellular allergy or toxicity tests are considered investigational and not medically necessary: 

• Antigen leukocyte cellular antibody test (ALCAT); or
• Basophil activation test (BAT); or
• Cytotoxic test; or
• HEMOCODE Food Tolerance System; or
• IgG food sensitivity test; or
• Immuno Blood Print test; or
• Leukocyte histamine release test (LHRT); or
• Mediator Release Test.

ALCAT
The antigen leukocyte cellular antibody test (ALCAT) measures whole blood leukocyte activity to identify allergens which cause an increase in the leukocyte activity. The ALCAT has been promoted as a diagnostic test for food allergy or intolerance (chemical sensitivity) and as a tool to establish elimination diets.

Mylek and colleagues (1995) explored the use of the ALCAT results as the base for elimination diet treatment in several conditions considered to be the result of food allergy (intolerance). A total of 72 participants (45 children and 27 adults), suffering from various symptoms of unproven etiologies and who had undergone a variety of treatments without improvement, were enrolled in the study. An ALCAT with 50 foods, skin prick test with 11 common inhalants and 28 foods and a detailed history were performed. Clinicians assessed whether the diet tailored on the basis of the ALCAT results achieved an improvement in symptoms after 1 month of an individual elimination diet. Emotional disturbances were assessed after the participants had been on the elimination diet for 4 months. The best results (83% improvement) were seen in symptoms related to arthritis. A 75% improvement was reported in urticaria, bronchitis and gastroenteritis. Less favorable results (32% improvement) were reported in childhood hyperactivity. The researchers concluded that “using the ALCAT Test in the course of allergologic diagnosis helps to describe less common foods that may cause reactions similar to that of apple, beetroots, lettuce, leek, pears, millet, oat or rice, etc.” Some of the limitations of the Mylek study include a lack of a definition of “emotional disturbances”, and the fact that detailed study methods and results were not published. The authors indicate that the study participants were assessed for symptom improvement after 1 month on the elimination diet and for improvement in emotional disturbances after 4 months on the elimination diet. However, the authors failed to report exactly what was evaluated during the clinical assessment, how the severity of symptoms were measured and failed to provide a breakdown of the results at the 1- and 4-month intervals. 

Several review articles have addressed unproven tests for allergy diagnosis (Hammond, 2018; Wuthrick 2005) and have concluded that the ALCAT test results are not reproducible and do not correlate with clinical symptoms.

The evidence-based allergy testing guidelines on food allergy from the American Academy of Allergy, Asthma and Immunology (AAAAI) and the American College of Allergy, Asthma and Immunology (ACAAI) (Sampson, 2014) do not mention ALCAT as one of the recognized tests for the evaluation of potential allergy.

Basophil Activation Test (BAT)

The 2008 AAAAI and ACAAI Practice Parameter on Allergy Diagnostic Testing stated: “A basophil activation test measured by expression of CD63 and CD203c and detected by flow cytometry is being evaluated for many IgE-mediated disorders. (C)” The Practice Parameter included a summary statement that, along with several other tests, “basophil activation tests are additional diagnostic tests for drug allergy. Further studies are required to confirm their clinical utility in the evaluation of drug allergic patients. (B)”

The AAAAI released an updated drug allergy practice parameter in 2022. It states the following regarding BAT: “In vitro testing for drug allergy with tests such as basophil activation tests, lymphocyte transformation tests, and other testing does not have any well-validated commercial assays in the United States and will not be discussed in this parameter”.

Guidelines published by the National Institute of Allergy and Infectious Diseases (NIAID) recommended “not using any of the following nonstandardized tests for the routine evaluation of IgE-mediated FA [food allergy]”. The list of tests includes “basophil histamine release/activation”. The guidelines further stated, “although the basophil histamine release/activation test is not a routine diagnostic test for IgE-mediated food allergies, it is commonly used in the research setting.” (Boyce, 2010).

Cytotoxic Testing
Cytotoxic testing is known by a variety of names, including but not limited to, Bryan's Test, the leukocytotoxicity test, the leukocytic food allergy test, the cytotoxic leukocyte test and the CYTOTOXIC test. A review by the Food and Drug Administration (FDA) concluded that the cytotoxic test is “An unproven diagnostic procedure unsupported by the scientific literature or well-controlled studies and clinical trials” (FDA, 1985). The 2008 AAAAI and ACAAI Practice Parameter statement concluded cytotoxic testing is one of the tests “for which there is no evidence of diagnostic validity”. NIAID does not recommend nonstandardized tests (cytotoxic testing) for the routine evaluation of IgE-mediated food allergies (Boyce, 2010).

IgG-Mediated Food Sensitivity Testing
Measurement of IgG and specifically IgG4 antibodies is frequently carried out in the research settings as diagnostic and prognostic tests to determine response to allergy treatments. Specific IgG/IgG4 results do not correlate with oral food challenges and are not recommended for diagnosing food allergies. The guidelines published by the AAAAI state that “measurement of food-specific IgG and IgG4 antibodies in serum are not recommended for the diagnosis of non–IgE-mediated food-related allergic disorders” (Sampson, 2014).

A 2018 review article by Hammond and Lieberman identified several studies evaluating food-specific serum IgG, but none of the studies were well-designed trials and many of them lacked controls.

The EAACI notes that testing for blood IgG4 against different foods is being more frequently performed with large-scale screening for hundreds of food items by ELISA-type and radioallergosorbent-type tests. However, many serum samples show positive IgG4 results in the absence of corresponding clinical symptoms. These findings, in conjunction with the lack of convincing evidence for the histamine-releasing properties of IgG4 in humans, and lack of any controlled studies on the diagnostic value of IgG4 testing in food allergy, do not provide any basis for the hypothesis that food-specific IgG4 results in food hypersensitivity. To the contrary, elevated IgG4 levels may indicate that an individual has been repeatedly exposed to food components, recognized as foreign proteins by the immune system. Its presence should not be considered as a factor which causes hypersensitivity, but rather as an indicator for immunological tolerance, linked to the activity of regulatory T cells. Food-specific IgG4 does not indicate (imminent) food allergy or intolerance, but rather a physiological response of the immune system after exposure to food components. Therefore, “Testing of IgG4 to foods is considered as irrelevant for the laboratory work-up of food allergy or intolerance and should not be performed in case of food-related complaints” (Stapel, 2008).

IgG antibody testing for food intolerance is generally offered by CLIA (Clinical Laboratory Improvement Amendments) approved laboratories. The BloodPrint^™ test (Immuno Laboratories, Fort Lauderdale, FL) is an example of a laboratory test that measures IgG response. There are several types of BloodPrint tests which vary by number. The numbers (154, 115, 88, 108 and 104) are indicative of how many different foods are being tested. Samples for the BloodPrint test can be drawn at a local laboratory or a physician’s office and sent to Immuo Laboratories for processing at a CLIA certified facility. A search of the peer-reviewed, scientific literature did not reveal any published studies for the BloodPrint test. 

The HEMOCODE^™ Food Tolerance System (Gemoscan, Ontario, Canada) is marketed as more than an IgG test. In addition to the test, it includes a “comprehensive program”, supervised by Doctors of Naturopathic Medicine. The system includes a preliminary face-to-face consultation and follow-up review of the test results with a health professional. The HEMOCODE Food Tolerance System is not available online but can be purchased through participating retailers. A search of the peer-reviewed, scientific literature did not reveal any publications related to the HEMOCODE test.

The US BioTek Laboratories (Shoreline, WA) IgG antibody assays (IgA and IgG) measure all 4 subclasses (IgG1 through IgG4) and are reported as a total IgG value on a semi-quantitative scale for each antigen. Information on the US BioTek Laboratories web site indicates that the panel is not available online but can be requested via a healthcare practitioner. A search of the peer-reviewed, scientific literature did not reveal any publications related to the US BioTek Laboratories antibody assessment panel.

The Complement Antigen Test (Sage Medical Laboratories, Ormond Beach, FL) measures IgG and components of complement to identify delayed food allergies. However, a search of the peer-reviewed, scientific literature did not reveal any publications related to the Complement Antigen Test. The Complement Antigen Test should not be confused with a complement assay or complement testing which measures the activity of the complement system. Unlike the Complement Antigen Test which measures circulating immune complexes (antibody-complement) response to delayed food allergies, complement testing is routinely carried out to diagnose and monitor certain autoimmune disorders, such as rheumatoid arthritis and systemic lupus erythematosus.  

Leukocyte histamine release test
In the leukocyte histamine release test (LHRT), leukocytes from the serum of an allergic individual are observed for the release of histamine in the presence of an antigen.

There is a lack of well-designed controlled studies evaluating the diagnostic and clinical utility of the LHRT. The AAAAI and ACAAI guidelines for allergy diagnostic testing indicate that the LHRT is a valuable research tool for in vitro investigations of allergy (Bernstein, 2008). 

Mediator Release Test
No published literature on the mediator release test (MRT^®), a patented test from Oxford Biomedical Technologies, was identified.

Allergy testing guidelines from the AAAAI and the NIAID do not mention the MRT as one of the recognized tests for the evaluation of potential allergy (Boyce 2010; Sampson, 2014).

Other Relevant Information

No FDA labeled indications have been identified for the tests included in this document. 

A Center for Medicare and Medicaid Services (CMS) Local Coverage Determination (LCD) on Allergy Testing (L36402) (2022) considers the ALCAT, BAT, cytotoxic test, IgG food sensitivity test, leukocyte histamine release test AND MRT as “experimental and investigational for allergy testing as these have not been proven to be effective or appropriate for the evaluation and/or management of IgE-mediated allergic reactions”. The HEMOCODE Food Tolerance System and Immuno Blood Print tests are not specifically mentioned in the LCD.

The CMS National Coverage Determination (NCD) on Food Allergy Testing and Treatment (1988) stated: “sublingual, intracutaneous, and subcutaneous provocative and neutralization testing and neutralization therapy for food allergies are noncovered.”

As discussed above, nationally recognized clinical practice guidelines from the AAAAI and the ACAAI do not recommend use of the allergy and toxicity tests included in this document.

According to the National Institute of Allergy and Infectious Diseases (NIAID), food allergies should be suspected in the following: (1) individuals presenting with anaphylaxis or select symptoms that occur within minutes to hours of ingesting food, especially in young children and/or if symptoms have followed the ingestion of a specific food on more than one occasion; (2) infants, young children and selected older children diagnosed with conditions such as moderate to severe atopic dermatitis (AD), eosinophilic esophagitis (EoE), enterocolitis, enteropathy, and allergic proctocolitis; and (3) adults diagnosed with EoE (Boyce, 2010).

The standard of care in the medical community for diagnosing food allergies includes a medical history, a physical examination and diagnostic tools, such as the percutaneous (scratch, prick, or puncture) tests, the allergen-specific serum IgE test, food elimination diets and oral food challenges (double-blind, placebo-controlled food challenge). 

Unproven blood, serum and cellular allergy and toxicity tests, addressed in this document, are described below.

ALCAT
ALCAT measures whole blood leukocyte activity to identify allergens which cause an increase in leukocyte activity. An electronic counter measures the change in number and size of leukocytes which have been incubated with purified food or mold extracts. A histogram is produced which reflects the cell count and cell size. The test samples are then compared with a "Master Control" graph. The ALCAT has been promoted as a diagnostic test for food allergy or intolerance (chemical sensitivities) in conditions such as, but not limited to arthritis, urticaria, bronchitis, gastroenteritis, childhood hyperreactivity, rhinitis, and atopic dermatitis. Typically, the results are used to establish elimination diets for these diseases. The ALCAT is manufactured by Cell Science Systems, Corp. (CSS), located in Deerfield Beach, Florida, which has a CLIA certified lab.

Basophil Activation Test (BAT)
The BAT is proposed as a test to determine allergic response, including food allergies and also insect vemon allergies, drug allergies and chronic urticaria. The BAT assesses response of basophils in a sample of fresh blood to allergen cross-linking IgE, using the activation marker CD63 or another activation marker such as CD203c. The BAT can be performed in most research laboratories using a flow cytometer, which can measure the fraction of reactive or activated basophils in the sample. There is a time limitation on performing the test on a blood sample since basophils have a half-life of less than a week (Hoffman, 2015).

Cytotoxic testing
Cytotoxic testing for food allergies is purported to be useful for diagnosing food allergies and food intolerances. The premise of cytotoxic testing is based on the theory that mixing an individual’s white blood cells with an antigen to which that individual is allergic, results in injury to the cells. This test involves the exposure of leukocytes to the presence of food extracts to which the individual is allergic. A technician then observes the unstained cells for changes in the size, shape, appearance or integrity. Swelling, vacuolation or other cytotoxic changes in cell morphology are taken as evidence of an allergic reaction to food. 

IgG-Mediated Food Sensitivity Testing
IgG antibody testing for food intolerance is based on the premise that elevated levels of IgG antibodies are an indicator of food intolerances. Immunoglobulin G (IgG) is frequently divided into four subclasses. Selective deficiencies in one or more of the four IgG groups may be seen in some individuals with repeated infections. IgG and IgG subclasses can be measured in a manner similar to those for allergen specific IgE. Controversy exists regarding whether increases of IgG4 are valid indicators of either diagnosis of a food allergy or clinical efficacy after immunotherapy. 

Leukocyte histamine release test
The leukocyte histamine release test (LHRT, basophil histamine release test) measures the amount of histamine released in the presence of an antigen. Varying concentrations of an allergen extract are added to the peripheral blood leukocytes of the individual being tested. Histamine is normally released as a result of the interaction of allergen with cell-bound IgE antibodies. If the individual is allergic to a specific antigen, the leukocytes should release histamine in-vitro upon stimulation of said antigen, unless the individual has recently been exposed and his/her cells are in a refractory state. A limited number of allergens can be tested using a single aliquot of blood.

Mediator Release Test
The MRT is a patented test from Oxford Biomedical Technologies (formerly the Signet Diagnostic Corporation). According to the manufacturer, the MRT measures volumetric changes in lymphocytes, neutrophils, monocytes and eosinophils after food or food-chemical challenges. Test results are reported as ‘non-reactive’, ‘moderately reactive’ or ‘reactive’ and can be used to develop a food sensitivity eating plan marketed by clinics operated by Oxford Biomedical Technologies.

Allergen: Any substance that can cause an allergic reaction.

Allergy: An acquired potential for developing adverse reactions that are mediated by the immune system (via IgE antibodies).

Antibody: A type of protein produced by the immune system in response to substances called antigens. 

Antigen: Any substance that, when introduced into the body, evokes an immune response and stimulates the production of antibodies.

Atopic dermatitis: A skin disease characterized by areas of severe itching, redness, and scaling.

Basophil: A type of white blood cell known as a granulocyte. Granulocytes consist of neutrophils and eosinophils, as well as basophils.

CLIA: Clinical Laboratory Improvement Amendments. Passed by the U. S. Congress in 1988, CLIA established quality standards for all non-research laboratory testing conducted on specimens obtained from humans for the purpose of providing information for the diagnosis, prevention, treatment of disease, or impairment of, or assessment of health.

Complement assay (test): A test that measures the activity of a group of 9 proteins (numbered C1-C9) that travel via the bloodstream, work with the immune system and play a role in the development of inflammation.

Gastroenteritis: Inflammation of the stomach and intestines.

Leukocytes: White blood cells.

Rhinitis: Inflammation and irritation of some internal areas of the nose; also referred to as a runny nose.

Urticaria: Red, raised areas of skin that are usually a sign of an allergic reaction; also referred to as hives.

The following codes for treatments and procedures applicable to this document are included below for informational purposes. Inclusion or exclusion of a procedure, diagnosis or device code(s) does not constitute or imply member coverage or provider reimbursement policy. Please refer to the member's contract benefits in effect at the time of service to determine coverage or non-coverage of these services as it applies to an individual member.

When services are Investigational and Not Medically Necessary:
When the code describes a procedure indicated in the Position Statement section as investigational and not medically necessary.

When services are also Investigational and Not Medically Necessary:
When the code describes a food allergy testing procedure indicated in the Position Statement section as investigational and not medically necessary.

Peer Reviewed Publications:

1. Antico A, Pagani M, Vescovi PP, et al. Food-specific IgG4 lack diagnostic value in adult patients with chronic urticaria and other suspected allergy skin symptoms. Int Arch Allergy Immunol. 2011; 155(1):52-56.
2. Beyer K, Teuber SS. Food allergy diagnostics: scientific and unproven procedures. Curr Opin Allergy Clin Immunol. 2005; 5(3):261-266.
3. Cabrera CM, Clarcast M, Palacios-Cañas A. Clinical validation of the basophil activation test in immediate hypersensitivity reactions to gadolinium-based contrast agents. Int Immunopharmacol. 2023; 117:110000.
4. Hammond C, Lieberman JA. Unproved diagnostic tests for food allergy. Imunol Allergy Clin N Am. 2018; 38: 153-163.
5. Khan DA, Banerji A, Blumenthal KG et al. Drug allergy: A 2022 practice parameter update. J Allergy Clin Immunol. 2022; 150(6):1333-1393.
6. Lieberman P, Crawford L, Bjelland J. Controlled study of the cytotoxic food test. JAMA. 1975; 231(7):728-730.
7. Myłek D. ALCAT Test results in the treatment of respiratory and gastrointestinal symptoms, arthritis, skin and central nervous system. Rocz Akad Med Bialymst. 1995; 40(3):625-629.
8. Niggemann B, Gruber C. Unproven diagnostic procedures in IgE-mediated allergic diseases. Allergy. 2004; 59(8):806-808.
9. Noh G, Ahn HS, Cho NY, et al. The clinical significance of food specific IgE/IgG4 in food specific atopic dermatitis. Pediatr Allergy Immunol. 2007; 18(1):63-70.
10. Wuthrich B. Unproven techniques in allergy diagnosis. J Investig Allergol Clin Immunol. 2005; 15(2):86-90.

Government Agency, Medical Society, and Other Authoritative Publications:

1. Bernstein IL, Li JT, Bernstein DI, et al. American Academy of Allergy, Asthma and Immunology (AAAAI) and the American College of Allergy, Asthma and Immunology (ACAAI). Allergy diagnostic testing: an updated practice parameter. Ann Allergy Asthma Immunol. 2008; 100(3 Suppl 3):S1-S148.
2. Boyce JA, Assa'ad A, Burks AW, et al. National Institute of Allergy and Infectious Diseases (NIAID). Guidelines for the diagnosis and management of food allergy in the United States: report of the NIAID-sponsored expert panel. J Allergy Clin Immunol. 2010; 126(6 Suppl):S1-S58.
3. Centers for Medicare and Medicaid Services. Local Coverage Determination for Allergy Testing (L36402). Effective 10/1/2022. Available at: https://www.cms.gov/medicare-coverage-database/view/lcd.aspx?lcdId=36402&ver=33. Accessed on April 4, 2024.
4. Centers for Medicare and Medicaid Services. National Coverage Determination for Food Allergy Testing and Treatment. NCD #110.11. Effective 10/31/1988. Available at: https://www.cms.gov/medicare-coverage-database/view/ncd.aspx?NCDId=266&ncdver=1. Accessed on April 4, 2024.
5. Sampson HA, Aceves S, Bock SA, et al. American Academy of Allergy, Asthma & Immunology (AAAAI); the American College of Allergy, Asthma & Immunology (ACAAI); and the Joint Council of Allergy, Asthma & Immunology (JCAAI) Joint Task Force on practice parameters. Food allergy: a practice parameter update–2014. J Allergy Clin Immunol. 2014; 134(5):1016-1025.
6. Stapel SO, Asero R, Ballmer-Weber BK, et al. European Academy of Allergy and Clinical Immunology (EAACI). Testing for IgG4 against foods is not recommended as a diagnostic tool: EAACI Task Force Report. Allergy. 2008; 63(7):793-796.
7. U.S. Food and Drug Administration. Inspections, Compliance, Enforcement, and Criminal Investigations. CPG Sec. 370.100 Cytotoxic Testing for Allergic Diseases. Revised 3/95. Available at: https://www.fda.gov/iceci/compliancemanuals/compliancepolicyguidancemanual/ucm123806.htm, Accessed on April 5, 2024.

1. American Academy of Allergy, Asthma, and Immunology (AAAAI). Available at:  http://www.aaaai.org/home.aspx. Accessed on April 5, 2024.
2. Department of Health and Human Services. Centers for Medicare and Medicaid Services. CLIA, Clinical Laboratories Improvements Amendments (CLIA). Available at: https://www.cms.gov/Regulations-and-Guidance/Legislation/CLIA. Accessed on April 5, 2024.
3. U. S. Food and Drug Administration. Regulatory Information. Guidance. Complementary and Alternative Medicine Products and their Regulation by the Food and Drug Administration. February 2007. Page last updated 5/6/2020. Available at: http://www.fda.gov/RegulatoryInformation/Guidances/ucm144657.htm. Accessed on April 5, 2024.

Antigen Leukocyte Cellular Antibody Test (ALCAT)
Basophil Histamine Release Test
BloodPrint Test
Bryan's Test (cytotoxic testing for food allergy)
Complement Antigen Test for delayed food allergies
Cytotoxic Leukocyte Test
CYTOTOXIC Test
HEMOCODE Food Tolerance System
IgG Food Sensitivity Testing
Leukocyte Histamine Release Test (LHRT)
Mediator Release Test
US BioTek Laboratories Antibody Assessment Panel

The use of specific product names is illustrative only. It is not intended to be a recommendation of one product over another, and is not intended to represent a complete listing of all products available.