Effect of peritoneal fluid from infertile women with endometriosis on ionophore-stimulated acrosome loss.

The effect of peritoneal fluid (PF) from endometriosis patients was studied in spontaneous and stimulus-induced (Ca-ionophore; A23187) acrosome reactions. PF samples were obtained from 21 infertile women with endometriosis and five normal women (controls). Sperm acrosomes were examined by staining with Pisum sativum agglutinin labelled with fluorescein isothiocyanate. The incidence of spontaneous acrosome reaction after 1 and 6 h of incubation (6.7 +/- 1.6 and 6.9 +/- 1.4 respectively) was significantly (P < 0.001) lower when the incubation was performed with PF from endometriosis patients in comparison with spermatozoa incubated in PF from the control group (12.8 +/- 1.1 and 12.8 +/- 0.8). Similarly, the incidence of A23187-induced acrosome reaction after 1 and 6 h of incubation (19.8 +/- 2.7 and 20.0 +/- 2.4) was significantly (P < 0.001) lower when spermatozoa were incubated with PF from endometriosis patients in comparison with spermatozoa incubated with PF from the control group (34.6 +/- 9.8 and 34.4 +/- 1.1). The incidence of A23187-inducible acrosome reaction was also significantly (P < 0.001) lower when the incubation was performed with PF from endometriosis patients (13.1 +/- 2.8 and 13.1 +/- 2.4) when compared with that from the control group (21.8 +/- 2.6 and 21.6 +/- 1.5). No relationship was found between the stage of endometriosis and the incidence of acrosome loss. In conclusion, the PF from endometriosis patients decreased both spontaneous and stimulus-induced acrosome reaction. This may represent a mechanism for the detrimental effect of the PF from endometriosis patients on the spermatozoa-oocyte interaction and partially explain the aetiology of infertility in patients with endometriosis.