- The prevalence rate of IgG and IgA antibodies to Chlamydia was analyzed in 50 women with laparoscopy-verified tubal infertility and in 50 age-matched control women by single serovar (L2) inclusion immunoperoxidase assay (IPA) and by immunoblotting technique (IB). Women with tubal infertility had significantly (p less than 0.001) elevated IPA Chlamydia IgG antibody titer greater than or equal to 128 and greater than or equal to 256 than controls (64% vs 16%. Odds ratios = 9.3 and 50% vs 10%, Odds ratio = 9 respectively). The prevalence rate of IPA IgA antibody titer (greater than or equal to 16) to Chlamydia was also significantly higher (p less than 0.001) in women with tubal infertility than controls (48% vs 8%, Odds ratio = 10.6). Antibodies to at least 19 chlamydial structural polypeptides ranging in molecular weight from 30 kD to 204 kD, were detected by the IB technique in the IPA seropositive sera. Antibodies to 57-60 kD were detectable in almost all the IPA IgG and IgA seropositive sera. The prevalence rate of IgG antibody to 57 kD-60 kD was significantly higher in women with obstructive infertility than healthy woman (84% vs. 56% p less than 0.01; Odds ratio = 3.8). More significantly, higher differences to 57-60 kD polypeptide were found in the case of IgA between the infertile women and controls (52% vs. 10%, p less than 0.001; Odds ratio = 9.7). The significance of IPA and IB technique for screening of infertile women is discussed.