Seminal plasma abrogates the postcoital T cell response to spermatozoal histocompatibility antigens

The T-cell responses to spermatozoal histocompatibility antigens were studied in the uterine regional lymph nodes of female rats by a specific cytoadhesion assay. The antigenic challenge was introduced either by artificial insemination with syngeneic or allogeneic epididymal spermatozoa or coitus. The uterine regional T-cell response to allogeneic spermatozoa following artificial insemination was measureable after 2 days and continued undiminished until day 5. In contrast, the measurable response to allogeneic coital challenge peaked on day 3 and disappeared by days 4-5. Since the difference between the two stimuli involved the presence of seminal plasma, these results indicate a possible immunoregulatory (suppressive) effect of seminal plasma on the cellular immune reaction of the female to the male alloantigens after mating.