Human sperm non-nuclear progesterone receptor expression is a novel marker for fertilization outcome

In a prospective, blind study, we have examined the relationship among theexpression of human sperm surface progesterone receptors, the ability toundergo a mannose-stimulated acrosome reaction and the rate offertilization in vitro. Individual aliquots of motile spermatozoa weresurface-labelled with progesterone and/or mannose-fluoresceinated ligands.Spontaneous acrosome loss and the increase in acrosome reactions followingexposure of spermatozoa to mannose ligands were assessed using rhodaminatedPisum sativum agglutinin. Progesterone fluoresceinated ligand binding wasobserved to occur in two patterns: (i) a uniform distribution of labellingover the acrosome cap (pattern II), and (ii) labelling limited to theequatorial and postacrosomal regions of the human sperm head (pattern III).A conversion of pattern II to pattern III binding was observed and wasassociated with the acrosome reaction. Pattern III binding was highlycorrelated with both fertilization potential and the ability to undergo amannose-stimulated acrosome reaction (P < 0.001). In contrast, normalsperm mannose receptor expression was seen in five men whose abnormalprogesterone receptor expression/function and inability to acrosome reactafter mannose treatment were correlated with their reduced fertility invitro. In conclusion, surface progesterone receptor aggregation enhancesthe mannose ligand-stimulated acrosome reaction. Such detection ofdefective sperm surface progesterone receptor expression/function may beuseful in the evaluation and management of male infertility.