Molecular identities of human sperm proteins reactive with antibodies in sera of immunoinfertile women.

Antisperm antibodies (ASA) can cause infertility in both men and women. It is important to delineate the sperm antigens against which these ASA are directed. Sperm proteins were separated by 2D gel electrophoresis and transferred to nitrocellulose membrane and incubated with sera from fertile women or immunoinfertile women having ASA. The corresponding immunoreactive peptide spots were cored from the gel and analyzed by the two-dimensional (2D) gel electrophoresis/matrix-assisted laser desoprtion ionization-time of flight-mass spectrometry and liquid chromatography-mass spectrometry (MALDI-TOF-MS/LC-MS). A total of 68 spots belonging to 38 different proteins and their isomers were identified. Fourteen of these proteins and their isomers reacted with both the fertile and immunoinfertile sera. Twenty-four of these proteins reacted specifically only with the immunoinfertile sera and not with the fertile sera. Among them was a novel protein designated as a hypothetical protein FLJ32704 (accession # Q96MA6). An immunodominant sequence (amino acid 151-159) of this protein was identified and a nonamer peptide based upon this sequence (IQTLG1TPR) was synthesized and examined for its immunoreactivity. This synthetic peptide reacted with 90% (36/40) of immunoinfertile sera and not with any of the fertile sera (0/40) in the enzyme-linked immnosorbent assay (ELISA). In conclusion, using the 2D gel electrophoresis/MALDI-TOF-MS/LC-MS procedure, we have identified several known and at least one novel antigen against which the antibodies are present in sera of immunoinfertile but not fertile women. Some of these antigens may find applications in specific diagonsis and treatment of infertility/immunoinfertility, and in the development of new generation of contraceptive modalities including contraceptive vaccines. (c) 2006 Wiley-Liss, Inc.