Problem: Recent studies in several laboratories are focused on delineating sperm antigens that are relevant to fertility and examining involvement of antibodies to these antigens in human immunoinfertility. Our laboratory has characterized two such antigens, namely fertilization antigen (FA-1) and YLP12 dodecamer sequence that are involved in sperm-oocyte binding. The present study was conducted to examine the occurrence of isoantibodies to various peptide epitopes of human and murine FA-1 antigen and YLP12 peptide in sera of immunoinfertile and fertile women.
Method of study: Sera from 67 immunoinfertile and 19 fertile women were collected. Various peptides based up on human and murine FA-1 antigen and YLP(12) were synthesized, and examined for immunoreactivity with these sera by using ELISA. Four immunodominant sequences, two each from human (hFA-1 82-97aa and hFA-1 200-219aa) and mouse (mFA-1 2-19aa and mFA-1 117-136aa) FA-1 antigen, were selected for the present study. Another human FA-1 sequence, hFA-1 220-240aa, that was not in the immunodominant region was used as a control.
Results: For human FA-1 peptides, 41.8% of the immunoinfertile sera reacted positively (>or=2 SD units) with hFA-1 82-97aa, 24.6% (16/65) with hFA-1 200-219aa, and 3% (2/66) with hFA-1 220-240aa peptide. For two murine FA-1 peptides, 41.7% (25/60) of the immunoinfertile sera reacted positively with mFA-1 2-19aa, and 41.5% (27/65) with mFA-1 117-136aa peptide. For the YLP12 dodecamer peptide, 43.3% (29/67) of the immunoinfertile sera reacted positively. None of the sera from fertile women reacted positively with any of these peptides.
Conclusion: In conclusion, our data indicate that the immunoinfertile women have circulating isoantibodies against at least two immunodominant peptide epitopes of human and murine FA-1 antigen and YLP12 peptide sequence. These peptides may find clinical application in the specific diagnosis and treatment of female infertility and contraceptive vaccine development.