Use of monoclonal antibodies for the detection of HLA and DR antigens on spermatozoa of different species

HLA expression on immature and mature human germ cells

Human leukocyte antigens (HLA) are membrane-bound glycoproteins encoded by the human major histocompatibility complex located on chromosome 6. They are known to function in immnunologic recognition and, with regard to reproduction, a number of non-immune functions have been proposed. Although the expression patterns of the major histocompatibility antigens have been extensively studied at the maternal fetal interface, there are still controversial reports on the expression of these molecules by human gametes and preimplantation stages. This brief review focuses on recent studies where the expression and distribution of HLA on human spermatogenic cells (spermatogonia, primary and secondary spermatocytes, spermatids, spermatozoa), primary and secondary oocytes, and preimplantation embryos have been investigated. These results, and their possible implications for the fertilization process and further embryonic development, will be presented.

HLA antigens and infertility with sperm autoantibodies in man

Vasectomized men with sperm auto-antibodies (S.A.A.) and high frequency of HLA-A20 antigen (Ag) were observed by Law et al. (1979); Hancock et al. (1983) observed the prevalence of HLA-A28 in infertile men with S.A.A. HLA-A, B and DR Ag were determined in a population of 80 Caucasian infertile men with (n = 22) or without (n = 58) agglutinating and/or cytotoxic S.A.A. in serum (S) and/or seminal plasma (SP), and the association between HLA-determinants and infertility with S.A.A. was investigated. The frequence of HLA-A28 Ag was found higher in the group with S.A.A. than without (18.2% vs 0.0%) but not statistically significant (chi 2 = 8.87; pc less than 0.15). The same result was obtained with HLA-B13 Ag (chi 2 = 8.87; pc less than 0.32). Lastly, there was no prevalence of HLA-DR Ag in men with S.A.A. In conclusion, no association was found between HLA-A, B and DR Ag and infertility with S.A.A. Nevertheless, two HLA-Ag were more frequently observed in the group with S.A.A.

Human leukocyte antigens (HLA) class I and class II on sperm cells studied at the serological, cellular, and genomic levels

The expression of human leukocyte antigens (HLA) on highly purified human ejaculated sperm cells was studied using the sensitive enzyme-linked immunosorbent assay (ELISA) technique and a wide panel of monoclonal antibodies to class I and class II HLA. In addition, the stimulatory capacity of these cells was tested in mixed cultures of lymphocytes and spermatozoa, and the levels of RNA homologous to the HLA class I and class II genes were determined. The results obtained using the ELISA indicate that the class I and class II HLA serologically defined antigens are weakly expressed on the cell surface of the mature spermatozoa. Highly purified sperm cells consistently stimulated heterologous lymphocytes but not when HLA-DR compatibility was observed between stimulator and responder. The proliferative response of lymphocytes induced by sperm cells was lower than the response obtained in a lymphocyte-lymphocyte combination, though the kinetics of the response were similar in both cases. In addition, it was found that spermatozoa contained RNA species homologous to HLA class II DR beta and DQ beta genes sequences but not to HLA class I sequences. The levels of these RNA species were significantly reduced after interferon stimulation. Lymphocytes that served as positive control were found to contain RNA complementary to both HLA class I and class II genes.

Failure to identify HLA ABC and Dr antigens on human sperm

An indirect radiolabeled antiglobulin assay (IRAA), adsorption procedures, and an indirect immunofluorescent assay using cytofluorometry (IFAA) failed to identify HLA ABC or D/Dr antigens associated with untreated human sperm or human sperm exposed to capacitating conditions. Two monoclonal clones against HLA ABC and two clones against Dr antigens were utilized. Test results in the IRAA were not different regardless of whether sperm from fertile men or human red blood cells were employed in the IRAA. However, there were highly significant differences in the IRAA between the HLA antigen expression of human sperm and leukocytes. If the antihuman HLA monoclonal antibody was preadsorbed with 25 X 10(6) sperm, there was no diminution in the ability of the adsorbed antibody to identify HLA antigens on leukocytes; however, preadsorption with 2.5 X 10(6) leukocytes reduced the activity of the monoclonal antihuman HLA antibody to levels equivalent to background activity.