Andrology: Variations in spontaneous and induced acrosome reaction: correlations with semen parameters and in-vitro fertilization results

To determine whether variations in spontaneous and induced acrosome reactions are correlated with semen quality, and to identify the inducers of clinical interest, the acrosome reaction, sperm concentration, motility and morphology were recorded in 117 semen samples from patients undergoing an in-vitro fertilization (IVF) attempt. The spontaneous acrosome loss after 24 h incubation in Menezo B2 medium and after induction by calcium ionophore A23187, progesterone, human follicular fluid, cyclic adenosine 3'-5'-phosphate (cAMP) analogue and phorbol ester (TPA) were measured using the fluorescein isothiocyanate-GB24 antibody. The mean (range) spontaneous acrosome reaction was 3.4 ± 0.6% (0.0-30.0). Response to the tested inducers was 23.3 ± 1.6% (0.0-72.0) for calcium ionophore, 5.4 ± 0.8% (0.0-60.0) for progesterone, 1.0 ± 0.7% (0.0-24.0) for human follicular fluid, 2.6 ± 0.7% (0.0-39.0) for the cAMP analogue and 2.3 ± 0.7% (0.0-31.0) for TPA. The response to calcium ionophore was correlated significantly to sperm concentration, motility and morphology, while the responses to progesterone and TPA were correlated significantly to motility and acrosome morphology. The responses to other inducers were not linked to classic semen parameters. When studying acrosome reaction as a function of IVF results, the responses to calcium ionophore and TPA were discriminant. The results of this study show that the spontaneous acrosome loss and the responses to acrosome reaction inducers are highly variable and partially linked to semen quality. The responses to calcium ionophore and TPA could be of interest in predicting the fertilizing ability in vitro.