Functional aspects of CD52 in reproduction.
CD52 is a GPI-anchored protein present in lymphocytes and male reproductive tissues (mrt) including mature sperm and seminal plasma. It has been shown that mrt-CD52 is synthesized in epithelial cells of the epididymis and vas deferens, but not in the testis. The mrt-CD52 is transported to mature sperm during sperm transition in the male reproductive tract. Lymphocyte CD52 functions to stimulate suppressor T cell induction, while mrt-CD52 is associated with seminogelin and involved in clot formation and liquefaction of semen. In a landmark study, a monoclonal antibody (Mab H6-3C4) from peripheral B lymphocytes of a patient with complement-dependent sperm-immobilizing antibody in the serum has been generated. Using Mab H6-3C4, the carbohydrate moiety of CD52 as an epitope for infertility-related antigen was identified. Mab H6-3C4 also shows strong complement-dependent sperm-immobilizing activity. This suggests CD52 may have a function in protecting sperm from complement activation. Indeed, purified mrt-CD52 from human sperm interferes with the classical pathway, but not lectin-binding or alternative pathways, of the complement systems. Recently, we found CD52 in ovulated cumulus cells from the female reproductive tissues (frt). The frt-CD52 is not recognized by Mab H6-3C4, suggesting that it harbors distinct carbohydrate antigenicity. Further studies are necessary to determine the molecular features and biological functions of CD52 in male and female reproductive tissues.
Koyama
Koji
K
Obstetrics and Gynecology, Laboratory of Developmental Biology and Reproduction, Advanced Medical Sciences, Hyogo College of Medicine, Nishinomiya, Japan. kkoyama@hyo-med.ac.jp
Hasegawa
Akiko
A
Komori
Shinji
S
D000818:Animals; D000911:Antibodies, Monoclonal; D015703:Antigens, CD / Q000502:physiology*; D000951:Antigens, Neoplasm / Q000502:physiology*; D001777:Blood Coagulation; D000074301:CD52 Antigen; D003171:Complement Pathway, Classical; D054885:Cumulus Cells / Q000378:metabolism; D005260:Female; D006023:Glycoproteins / Q000502:physiology*; D017261:Glycosylphosphatidylinositols / Q000502:physiology*; D006801:Humans; D007108:Immune Tolerance; D008297:Male; D012098:Reproduction / Q000502:physiology*; D013081:Sperm Motility; D013094:Spermatozoa / Q000276:immunology / Q000378:metabolism*; D050378:T-Lymphocytes, Regulatory / Q000378:metabolism
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000951:Antigens, Neoplasm; D000074301:CD52 Antigen; C000613862:CD52 protein, human; D006023:Glycoproteins; D017261:Glycosylphosphatidylinositols