Leukocyte detection in human semen using flow cytometry

This study set out to establish a new method, using flow cytometry, to eval uate leukocytes in semen. Ejaculates of 59 males, asymptomatic for genitour inary infections, were examined. Routine semen analyses were carried out as well as peroxidase and polymorphonuclear granulocyte-elastase detection, L eukocytes were detected combining flow cytometry and monoclonal antibodies (anti-CD45, anti-CD53). This technique reliably assessed the total number o f leukocytes and differentiated subpopulations even at low concentrations, The peroxidase test and elastase determination showed good specificity, but only moderate sensitivity versus flow cytometry combined with monoclonal a ntibodies, No significant association was observed between semen parameters and leukocytospermia whether evaluated by conventional methods or flow cyt ometry except for a moderate correlation between spermatozoa and CD53-posit ive cell concentrations. A first comparison of data from patients grouped o n the basis of leukocytospermia (>10(6) white blood cells, WBC/ml) or non-l eukocytospermia revealed no significant differences in semen parameters; lo wering the threshold value for leukocytospermia to 2 x 10(5) WBC/ml, sperm concentration was reduced in the group with a low number of WBC identified by monoclonal antibodies. Flow cytometry using monoclonal antibodies was se en to be a simple, reproducible method that enables leukocytes in semen to be accurately detected and to identify WBC subpopulations without prelimina ry purification procedures.