Serodiagnostics of chlamydial infections--significance of positivity in IgA and/or IgM antibody classes only.

There was followed the development of serological findings in patients with proved positivity only in classes IgA and/or IgM of chlamydial antibodies (without IgG), which can be suspected of showing "false" positivity. 184 patients were repeatedly examined for chlamydial antibodies in their sera (interval between collections up to three months) using a genus specific rELISA. Sera were also tested for the evidence of IgM antibodies against capside antigen of Epstein-Barr virus (EBV) and against cytomegalovirus (CMV) using ELISA methods. In 75 (40.8%) of patients, IgA/IgM individual positivities were demonstrated even during the following sample test(s). In 28 (15.2%) of them, IgG evidence preceded and in 29 (15.7%) other patients positive seroconversion followed in this class. In 13 (7.1%) patients, IgG antibodies disappeared and subsequently reappeared. Only in 39 (21.2%) of these probands, antibodies IgA/IgM were not demonstrated at another examination. Active EBV, resp. CMV infection was proved in 24 (13.0%), resp. in 18 (9.8%) of patients. It is concluded that the evidence of positivities only in classes IgA and/or IgM mostly signal the onset of a primary infection (reinfection) or an active infection in patients with IgG production failures respectively. In these cases, a "false" positivity can be supposed to occur only in a minor extent.