Diversity of Antisperm Antibodies Bound to Sperm Surface in Male Immunological Infertility

PROBLEM: The presence of antisperm antibodies (ASA) in males can reduce fecundity, however, relationship between the two is disputed. This study was performed to investigate if there is diversity of ASA bound to sperm surface using immunobead test (IBT) combined with complement dependent sperm immobilization test (SIT). METHODS: The ASA bound to sperm surface were detected using the direct IBT (D‐IBT) in 275 semen samples. In some cases with ASA detected by D‐IBT, sperm immobilizing antibodies bound to sperm surface were also evaluated using direct SIT (D‐SIT). RESULTS: The incidence of the immunoglobulin G (IgG), IgA, and IgM classes of ASA detected by D‐IBT were 2.5, 1.8, and 0.4%, respectively. Totally, nine (3.3%) infertile men had ASA on the sperm surface. D‐SIT was tested positive in four (66.7%) of six cases with ASA assessed by D‐IBT. CONCLUSIONS: Some of the sperm‐bound antibodies are associated with complement dependent sperm immobilizing antibodies, indicating that there exists a heterogeneity of sperm‐bound antibodies. This result might be one of the reasons for the controversy about the relationship between ASA and immunological infertility in men.