The Alcat test (English A ntigen L eukocyte C ellular A ntibody T est) or Leukozytenaktivierungstest on immunostimulants is as cellular allergen stimulation test an inserted in alternative medicine diagnostic method for the qualitative determination of food intolerance . It is based on the hypothesis that food intolerance can be caused by an inflammatory reaction to certain foods. By measuring the patient's blood responses to a variety of food extracts and food additives, the patient is advised which foods to avoid. The procedure or its informative value is not scientifically supported.
The ALCAT test is a further development of the test developed by Black and Bryan in the late 1950s, known as the cytotoxic food test (English leucocytotoxic test. Or Bryan's test ). "Bryan's Test" is based on the microscopic assessment of activation-induced changes and autolysis of the leukocytes after mixing the blood with allergens and food extracts. It was denied approval in the United States because it was unsuitable for detecting allergies. Before 1975, however, no strict distinction was made between the various types of allergic reactions.
The ALCAT method is based on an activation-induced change in the size of the leukocytes or granulocytes after mixing the patient's blood with food extracts. The underlying mechanisms were described by Hurd and Hashimoto, among others, and examined in detail by Grinstein et al.
The Alcat test is therefore an in vitro assay in which the activation of the detection of an immune response against the antigens tested in whole blood, here leukocytes , in particular neutrophilic granulocytes , after incubation of the blood is determined with purified extracts of foods. This activation is accompanied, among other things, by a change in the size of the cells. Neutrophil granulocytes have IgG and IgA receptors on their surface , to which antibodies bind with their Fc part. If the specific antigens bind to these antibodies, the cells are activated. If the activation of the cells is triggered by IgG antibodies, it must be assumed that they are essentially antibodies of the isotypes IgG1 and IgG3. Since neutrophil granulocytes do not have IgE receptors, classic IgE- mediated type I allergies are not recorded by the ALCAT test and should therefore be excluded beforehand using suitable test methods.
The actual reactions are carried out in standardized, pre-assembled test cassettes equipped with the test substances. The measurement is then carried out automatically in a modified measuring system based on the Coulter cell counter. The strength of the reaction is calculated using the difference between the individual measurement curves and negative controls.
The test is available as a self-payer service that is not covered by statutory health insurance in Germany .
Usual diagnostics for food allergies and intolerances
Immediate type food allergies are usually detected by means of an IgE antibody test with a simultaneous positive oral provocation test. If a type IV allergy is clinically suspected, the atopy patch test or (in the case of contraindications) the lymphocyte transformation test is carried out.
Allergen-specific antibodies of isotype G can be detected in sera from healthy as well as atopic individuals. The formation of allergen-specific antibodies of the immunoglobulin class IgG is part of the normal immune response to exposure to foreign substances or food. There is no correlation between the clinical symptoms and the immediate allergic type reaction. With regard to their disease relevance, the importance of antibodies is completely uncertain.
The classic method for the detection of food intolerances consists in a low allergen diet for several weeks with subsequent step-by-step provocation either with individual foods or so-called "supermeals", in which a large amount of a selection of (pseudo) allergens is consumed. However, the method is very time-consuming and can therefore only be used to identify a limited number of antigens.
Evaluation of the ALCAT test
The ALCAT procedure must be classified as a controversial procedure. In addition to the very complex procedure of the elimination diet with subsequent provocation (see above), there is no established method for determining food intolerances that has been adequately proven in clinical studies . However, these problems are also inherent in the nature of the matter. Clinical studies that would allow a clear statement for or against the ALCAT test are pending. In addition, it is often found that the test would be unsuitable for determining a food allergy , but this is not the aim of the method.
According to Jörg Kleine-Tebbe and others, "the ALCAT test with food or additives, previously known as a cytotoxic food test ... is unsuitable for diagnosing NMA or NMI" (NMA: food allergy ; NMI: food intolerance ).
The German Society for Allergology and Clinical Immunology (DGAI) and the Medical Association of German Allergologists (ADA) declared the test to be unsuitable for clarifying or excluding a food allergy.
Potter et al. Presented their negative opinion on the ALCAT test in a short letter to the South African Medical Journal and justified this with the small number of existing studies on the test procedure.
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- Adrian Morris: Complementary and alternative allergy tests. In: Current Allergy & Clinical Immunology. Vol 19, March 2006, No. 1. (PDF) ( Memento of the original from March 3, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
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- In vitro diagnostics of food allergies. Position paper of the German Society for Allergology and Clinical Immunology (DGAI) and the Medical Association of German Allergologists (ÄDA) (full text)
- PC Potter et al: The ALCAT test - inappropriate in testing for food allergy in clinical practice. In: South African Medical Journal. 81 (7), 1992 Apr 4, p. 384.
- Lymphocyte transformation test LTT: A method for determining the activation of T lymphocyte T cells by antigens. Also suitable for measuring type IV allergies.
- C. Blindsev-Jensen, LK Poulsen: What do we at present know about the ALCAT test and what is lacking? In: Monogr Allergy. 32, 1996, pp. 228-232. PMID 8813206
- PC Potter, J. Mullineux, EG Weinberg, M. Haus, P. Ireland, C. Buys, C. Motala: The ALCAT test - inappropriate in testing for food allergy in clinical practice. In: South African Medical Journal. 81 (7), 1992 Apr 4, p. 384. PMID 1561573