SUPPRESSION OF RAT EPIDIDYMAL SPERM IMMUNOGENICITY BY A SEMINAL-VESICLE SECRETORY PROTEIN AND TRANSGLUTAMINASE BOTH IN-VIVO AND IN-VITRO

The pretreatment of epididymal spermatozoa with SV-IV, one of the majo r secretory protein produced by the epithelium of adult rat seminal ve sicles, was found to markedly decrease their ability to induce in vivo peritoneal macrophage activation, measured as class II major histocom patibility complex surface antigen expression, superoxide anion produc tion, phagocytic activity, and antigen presentation. In addition, the treatment of spermatozoa with SV-IV produced a significant decrease of their immunogenicity evaluated in vitro by [H-3]thymidine incorporati on in splenocyte/spermatozoon co-culture. The concurrent presence of S V-IV and transglutaminase, an enzyme secreted in large amounts from th e rat anterior prostate, amplified these phenomena. The suppression of the epididymal sperm immunogenicity is suggested to be of crucial imp ortance for the prevention of the immune response to the sperm introdu ced in the immunocompetent female genital tract during coitus.