Oral immunization with sperm antigens: possible therapy for sperm antibodies?

Young adult male CD-1 mice were given intraperitoneal injections (IP) of saline (controls) and pooled sperm or seminal plasma of two autoimmune infertile men and two nonautoimmune fertile men (n = 40 per treatment). Other mice received only an oral challenge with the same antigens (oral controls; n = 20 per treatment). Three weeks after the booster challenge (day 36), 20 mice in each group were orally immunized with the antigens, whereas the other 20 were not (IP controls). Cytotoxic antibody titers (immunoglobulin M) to human sperm were significantly higher in mice IP immunized with sperm or seminal plasma from autoimmune infertile men or orally immunized with autoimmune men's sperm, in contrast to the controls. Oral challenge with sperm or seminal plasma of autoimmune infertile men after the IP immunization with the same resulted in significantly decreased cytotoxic sperm antibody titers (P less than 0.001 versus oral or IP controls in sperm immunization; P less than 0.001 versus IP controls in seminal plasma immunization). Fertility was unaffected by any mode of immunization. It is concluded that, in mice, sperm and seminal plasma antigens from autoimmune infertile men are more immunogenic than those from nonautoimmune fertile men, and oral challenge with the former after an IP establishment of cytotoxic sperm immunity desensitizes the immune mice. These findings may have practical implications in the diagnosis and immunotherapy of infertile men with cytotoxic sperm antibodies.