The authors state that sperm apoptosis is a useful indicator of male infertility in the case of varicocele, while being unable to detect Fas and Fas-L on sperm cells. At the same time, they also claim that the presence of Fas is a debated issue. We demonstrated beyond any reasonable doubt that Fas is not present in human sperm and clarified that detections of Fas from other authors were due to interference with leukocytes in seminal samples. To prove this, we performed semen analysis through a multiparameter flow cytometry method that excluded leukocytes from the sperm population.
