Stimulation of oxidant generation by human sperm suspensions using phorbol esters and formyl peptides: Relationships with motility and fertilization in vitro

Objectives: To investigate the influence of reactive oxygen species generated by human spermatozoa and contaminating leukocytes on sperm movement and fertilization in vitro. Design: A chemiluminescence technique, using luminol and peroxidase, was used to monitor the generation of reactive oxygen species by human sperm suspensions and the results were correlated with sperm movement and the fertilization of human ova in vitro. Setting: Diagnostic Andrology Laboratory and IVF Clinic. Patients: Infertile couples undergoing IVF therapy. Results: An N-formyl-methionyl-leucyl-phenylalanine (FMLP) provocation test was used to demonstrate that the presence of leukocytes in 28.5% of the sperm preparations was associated with elevated levels of spontaneous reactive oxygen species production, impaired movement, and a reduced capacity for fertilization in vitro. In the absence of leukocytes, exposure to phorbol ester stimulated a burst of reactive oxygen species generation by human spermatozoa, the magnitude of which was correlated highly with a loss of sperm motility but not with fertilization rates observed in the concurrent IVF cycle. Conclusion: Leukocyte contamination of human sperm preparations can be detected readily by FMLP-induced, luminol-dependent chemiluminescence and the results have an important bearing on the fertilizing capacity of the spermatozoa in vitro.