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

The immune response to coitus and conception

It is well recognized that cells or tissues exchanged between genetically dissimilar members of the same species will be destroyed by a specific immune response. This process of destruction is initiated by the expression of histocompatibility antigens on the surface of the donor cells which provoke a reaction by the immune system of the recipient. Successful reproduction even through a fundamental process is thought to expose the female to significant antigenic challenge. Numerous hypotheses have been proposed to account for the survival of the semiallogeneic conceptus, although the immunological consequences of coitus are frequently ignored. The possible immunosuppressive role of seminal plasma in normal reproduction is clearly of great clinical importance. Its exclusion from the in vitro fertilization techniques of human reproduction may partially account for the high failure rates associated with this form of assisted reproduction. Its presence in the normal ejaculate may explain the vulnerability of the female reproductive tract to virally inducted neoplasms and be a relevant factor in the etiology of the acquired immune deficiency syndrome.

A comprehensive search for segregation distortion in HLA

Segregation distortion, the non-Mendelian segregation of gametes, has been well documented among diverse groups of organisms. These cases are characterized by extreme segregation ratios found only in males. Previous reports have suggested the existence of segregation distortion operating in the HLA system of humans, a tightly linked complex of genes which regulates the immune system. In mice, some alleles of the T/t complex, which is linked to H-2 (the HLA homologue of mice), cause extreme segregation distortion in wild mice populations. Here we report on the examination of a large body of pedigree data on non-diseased families, scored for the alleles of five HLA region loci. We searched for segregation distortion on the basis of five different models of inheritance: allelic, haplotypic, genotypic, diffuse occurrence in families, and autosomal effects on the sex ratio. There was no clear evidence for segregation distortion. In particular, the possibility of extreme levels of segregation distortion was firmly rejected in the populations examined, thus reducing the likelihood of common distortion-causing HLA associated haplotypes in our species.

Assessment of immune responses to H-Y antigen in naturally inseminated and sperm-injected mice using cell-mediated cytotoxicity assays

An in vitro cell-mediated cytotoxicity assay has been used to assess immunity to the male-specific H-Y antigen in female mice after either insemination with male cells at syngeneic natural mating or after injection with syngeneic sperm cell suspensions. Lymphocytes showing specific cytotoxicity for the H-Y antigen could be recovered from both spleen and lymph nodes of female mice injected with sperm. However, insemination of male cells at natural mating did not apparently prime cytotoxic cells against the H-Y antigen in either the spleen or para-aortic lymph nodes draining the uterus of female mice mated once or repeatedly (3-10 X) in the absence of pregnancy. These results are discussed in relation to the factors regulating the immune responsiveness of the female to inseminated antigens.