Detection of Antisperm Antibodies by Indirect Flow Cytometry: Comparison with Direct Mixed Agglutination Reaction Test

<p><strong>Background and Objectives:</strong> The immunobead binding test (IBT) and the mixed agglutination reaction (MAR) are the most commonly used methods for detection of antisperm antibodies (ASA). The detection of ASA by flow cytometry (FCM) was first described by Haas and Cunningham. Both assays can be performed as direct or indirect methods. In this study, indirect FCM was compared with the direct MAR for detection of ASA. </p><p><strong>Methods:</strong> Semen samples were obtained from 80 men (infertile couples) in Isfahan Fertility and Infertility Center. Seminal plasma samples were incubated with ASA-negative donor sperm. Then, surface-bound antibody was detected with FITC-labeled antihuman immunoglobulin directed against IgA and IgG in the indirect FCM assay. ASAs bound to the surface of patients’ sperm were detected by direct MAR test. </p><p><strong>Results:</strong> The indirect FCM correlates with direct MAR for detection of IgA antisperm antibodies (r=0.55 and P=0.006). The indirect FCM, however, does not correlate with direct MAR for the detection of IgG antisperm antibodies (r=0.25 and P=0.25). </p><p><strong>Conclusion:</strong> Some of the ASAs in seminal fluid bind to spermatozoa. Therefore, indirect tests to detect ASAs in seminal plasma are likely to miss the presence of IgG antisperm antibodies while they effectively detect IgA antisperm antibodies. </p&gt