Development and validation of a fluorescent microsphere immunoassay for anti-IgA.
Anti-IgA may cause anaphylactic transfusion reactions in IgA-deficient individuals. Testing for IgG anti-IgA is useful to identify persons at risk. This report describes an immunoassay for anti-IgA that uses polyclonal IgA coupled to fluorescent microspheres as an immunosorbent. Anti-IgA is detected by phycoerythrin-labeled anti-IgG. The assay is calibrated in arbitrary units by use of a serum that contains anti-IgA. Dose-response studies with sera that contain anti-IgA showed positive responses at dilutions up to 32-fold greater than the dilution used to test patients' samples. Inhibition studies with purified IgA and IgA-deficient serum showed no inhibition with IgA-deficient serum and complete inhibition with soluble IgA. Clinical tests performed in more than 90 assays had a CV of 13.6 percent for measurements of an internal positive control. The fluorescent immunoassay method is rapid, reproducible, and sensitive to low concentrations of IgG anti-IgA.
Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905, USA.
K M
KM
Rumilla
J L
JL
Winters
J M
JM
Peterman
E A
EA
Jedynak
H A
HA
Homburger
D000707:Anaphylaxis / Q000097:blood / Q000175:diagnosis / Q000276:immunology; D000888:Antibodies, Anti-Idiotypic / Q000097:blood*; D019085:Fluorescent Antibody Technique, Direct; D006801:Humans; D017098:IgA Deficiency / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D008863:Microspheres; D012680:Sensitivity and Specificity
D000888:Antibodies, Anti-Idiotypic; D007074:Immunoglobulin G; C049937:anti-IgA