Phagocytosis of human post-capacitated spermatozoa by macrophages.
BACKGROUND
Earlier studies demonstrated that macrophages phagocytize spermatozoa in the female genital tract of mammals. In spite of this phagocytosis, fecundity is not affected, raising questions of how the resulting decrease in the number of spermatozoa does not reduce the fertilization rate and of the role of this phagocytosis. We hypothesized that its role is to rid the female genital tract of spermatozoa past their fertilizing stage (post-capacitated spermatozoa). Here we examined whether, indeed, phagocytosis is restricted to post-capacitated spermatozoa.


METHODS
Spermatozoa were incubated for 22 h either in a medium that allows them to become capacitated and then post-capacitated, or in a medium that prevents them from acquiring these states. These sperm populations were compared for their susceptibilities to macrophage phagocytosis.


RESULTS
Phagocytosis was significantly higher (P << 0.001) in the sperm population containing post-capacitated spermatozoa. Vitality, motility, the acrosomal status and the proportion of capacitated cells did not affect phagocytosis.


CONCLUSIONS
Post-capacitated spermatozoa are, probably, preferentially phagocytized by macrophages.
Oren-Benaroya
Rony
R
Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot, Israel.
Kipnis
Jonathan
J
Eisenbach
Michael
M
D000177:Acrosome; D020101:Acrosome Reaction; D002470:Cell Survival; D002633:Chemotaxis; D015925:Cryopreservation; D003470:Culture Media / Q000378:metabolism; D005260:Female; D005306:Fertilization; D006801:Humans; D008264:Macrophages / Q000166:cytology* / Q000378:metabolism; D008297:Male; D010587:Phagocytosis; D013075:Sperm Capacitation; D013081:Sperm Motility; D013094:Spermatozoa / Q000378:metabolism* / Q000473:pathology*
D003470:Culture Media