Expression of decay-accelerating factor (CD55) of the complement system on human spermatozoa.
Human spermatozoa were analyzed for their expression of decay-accelerating factor (DAF, CD55), a glycolipid-anchored regulatory protein of the C casade. Morphologic data showed that DAF was localized at the acrosomal region of the sperm head. Analysis with anti-DAF antibody-immunoprecipitated proteins of acrosome-reached spermatozoa revealed a 44- to 54-kDa protein. Carbohydrate analysis of sperm DAF indicated that it contains nonsialated N- and O-linked sugars. The absence of mature oligosaccharides on this protein appears to account for the difference in molecular mass between sperm DAF and the 70-kDa DAF expressed on other human tissues. Sperm DAF reinserted into sheep E and inhibited C-mediated lysis. This effect was reversed by mAb, which block DAF function. These results indicate that sperm DAF also possesses a glycolipid anchor. The expression of DAF on acrosome-reacted spermatozoa suggests that it may act concomitantly with other C regulators such as membrane cofactor protein to modulate the activation of C in the immunocompetent female genital tract and protect acrosome-reacted spermatozoa from C-mediated attack.
Cervoni
F
F
Institut National de la Santé et de la Recherche Médicale, Faculté de Médecine, Nice, France.
Oglesby
T J
TJ
Fénichel
P
P
Dohr
G
G
Rossi
B
B
Atkinson
J P
JP
Hsi
B L
BL
D000177:Acrosome / Q000502:physiology; D000818:Animals; D015703:Antigens, CD / Q000032:analysis*; D018958:CD55 Antigens; D002241:Carbohydrates / Q000032:analysis; D003169:Complement Inactivator Proteins / Q000032:analysis*; D006801:Humans; D008297:Male; D051916:Membrane Cofactor Protein; D008562:Membrane Glycoproteins / Q000032:analysis*; D011817:Rabbits; D013077:Sperm Head / Q000276:immunology; D013094:Spermatozoa / Q000276:immunology*
D015703:Antigens, CD; C497857:CD46 protein, human; D018958:CD55 Antigens; D002241:Carbohydrates; D003169:Complement Inactivator Proteins; D051916:Membrane Cofactor Protein; D008562:Membrane Glycoproteins