Evaluation of Fas positive sperm and complement mediated lysis in subfertile individuals

Evaluation of Fas receptor on surface of sperm, as an apoptotic marker, using flow cytometry and confirming the results using an antibody-antigen complex through the classic complement pathway.

Semen samples were obtained from 10 fertile and 73 infertile individuals with diagnoses of male factor infertility. Expressions of Fas receptor and phosphatidyl serine on sperm were assessed by flow cytometry. Fas expression was further assessed by antibody-antigen complex through the complement pathway. Lysis was detected via PI (propidium iodide) staining.

The mean Fas expression was considerably lower than previously reported values. No significant differences in the percentage of PI were detected before and after activation of the classic complement pathway. Annexin V positive samples showed low Fas expression.

Our results have confirmed the presence of selected apoptotic markers such as Fas or phosphatidyl serine on ejaculate sperm, but suggest that Fas expression is low. Further studies are required to investigate the "abortive apoptosis" mechanism through Fas/Fas L.