Method Description

Immunoglobulin A (IgA) anti-Saccharomyces cerevisiae antibodies (ASCA) are measured by commercial, microtiter enzyme immunoassay. Partially purified and disrupted S cerevisiae is bound to the wells of a polystyrene microtiter plate coated with purified mannan from the cell wall of S cerevisiae. Prediluted controls and diluted patient sera are added to separate wells, allowing any anti-S cerevisiae antibodies (ASCA) IgG or IgA antibodies present to bind to the immobilized antigen. Unbound sample is washed away, and a horseradish peroxidase-conjugated anti-human IgA antibody is added to each well. A second incubation allows the enzyme-labeled anti-human IgA to bind to any patient antibodies, which have become attached to the microtiter wells. After washing away any unbound enzyme labeled anti-human IgA, the remaining enzyme activity is assessed by adding a chromogenic substrate and measuring the intensity of the color that develops. The assay is evaluated by spectrophotometrically measuring and comparing the color intensity that develops in the patient wells with the color in the control wells. Results of the test for IgA ASCA are reported in relative units per milliliter (RU/mL).(Package insert: Anti-Saccharomyces cerevisiae ELISA (IgA). EUROIMMUN Medizinische Labordiagnostika AG; 05/2011)