[The clinical significance of specific IgA antibodies in local secretions in cases with chlamydial urogenital infections--comparison with serum antibodies and analysis of antigen specificity by immunoblotting assay]

Abstract

IgA antibody titers to C. trachomatis in local secretions were measured by immunoperoxidase assay (Savyon kit) in male and female cases with various urogenital infections, and the clinical significance of IgA antibody in the local secretion was discussed. In addition, the antigen specificity of the IgA for C. trachomatis in the local secretions was analyzed by immunoblotting assay. 1) In female cases with cervicitis and male cases with urethritis, the positive rate of IgA antibody in their secretions was higher in cases with C. trachomatis antigen than in those without it. In addition, the IgA antibody titers in their secretions tended to be higher than in serum, suggesting that the result reflected a local immune response at the site of infection. 2) In cases with chronic prostatitis, a condition in which detection of antigen at the site of infection was difficult, the positive rate of IgA antibody in prostatic secretion was 23.6%. We confirmed that most of the IgA antibodies in prostatic secretions were of the secretory type. 3) IgA antibodies in secretions reacted to the major outer membrane protein (MOMP) and 60-Kd polypeptides of the outer membrane of C. trachomatis by immunoblotting assay, proving that they were the secretory IgA antibodies specific for C. trachomatis. These results described above confirmed that measurement of IgA antibody titers in local secretions by immunoperoxidase assay and immunoblotting assay was useful for the diagnosis of chlamydial urogenital infections such as chronic prostatitis, which the antigen detection was usually difficult. Examination of IgA antibody in local secretions was considered to be useful for making a correct diagnosis even in cases who were suspected to have C. trachomatis infection but showed negative antigen.