The ALCAT test, or antigen leukocyte antibody test, is one that claims to measure adverse reactions to dietary substances. It was created by American Medical Testing Laboratories and is now marketed by Cell Science Systems (also known as ALCAT Diagnostic Systems) of Deerfield Beach, Florida.
Research published up to 2010 did not support the test or provide evidence that it was a reliable medical diagnostic tool; since it had not been validated.  In a position statement, the Australasian Society of Clinical Immunology and Allergy classified the ALCAT with other forms of cytotoxic tests as inappropriate tests, saying of them
"These results have been shown to not be reproducible, give different results when duplicate samples are analysed blindly, don't correlate with those from conventional testing, and 'diagnose' food hypersensitivity in subjects with conditions where food allergy is not considered to play a pathogenic role."
A small study conducted in 2014 demonstrated reactions identified as "severe" were associated with the up-regulation of CD11b on CD4+ and CD8+ T cells, suggesting a basis for further research into the mechanisms alleged.
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- "Food reactivity on the ALCAT leukocyte activation test is associated with upregulation of CD11b on T cells". ResearchGate. Retrieved 2017-11-22.