Interference of immunoglobulin G (IgG) antibodies in IgA antibody determinations for Chlamydia pneumoniae by microimmunofluorescence test

Abstract

In the microimmunofluorescence test for measuring immunoglobulin A (IgA) antibodies against Chlamydia pneumoniae, removal of interfering IgG antibodies made IgA antibody reactivity patterns in 952 serum samples easier to interpret, prozone effects disappeared, and titers increased, especially in the sera with high IgG titers. IgA rheumatoid factors did not interfere in the assay.