Evaluation of chemiluminescence and flow cytometry as tools in assessing production of hydrogen peroxide and superoxide anion in human spermatozoa

ObjectiveTo examine simultaneously the levels of hydrogen peroxide (H2O2) and superoxide (O2−
• ) using chemiluminescence and flow cytometry.DesignProspective laboratory study.SettingReproductive research lab in a tertiary hospital.Patient(s)Semen samples from 18 healthy male volunteers.Intervention(s)Sperm preparation and measurement of reactive oxygen species (ROS) by chemiluminescence using luminol and lucigenin before and after H2O2 exposure and by flow cytometry using dichlorofluorescin diacetate (DCFH-DA) for H2O2 and dihydroethidium (DHE) for O2−
• .Main Outcome Measure(s)Sperm count, motility, viability, and ROS levels.Result(s)Immature sperm fractions showed significantly higher levels of ROS measured by either luminol or lucigenin compared with the neat and mature fraction. ROS levels were detectable by flow cytometry in chemiluminescence-negative samples. Both mature and immature sperm fractions had a significantly higher percentage of cells positive for H2O2 compared with neat semen. On the other hand, the percentage of O2−
• -positive cells in neat semen was significantly higher compared with the percentage found in mature fractions but significantly lower than that in the immature sperm fractions.Conclusion(s)We recommend ROS measurement by flow cytometry on the basis that it requires a lower sperm count, is comparable to chemiluminescence, and has higher specificity for intracellular ROS in viable spermatozoa. Samples tested negative by chemiluminescence still may have high intracellular H2O2 generation that can be detected by flow cytometry.