Reactive oxygen species generated by human neutrophils inhibit sperm motility: protective effect of seminal plasma and scavengers

Abstract

To investigate whether activated poly-morphonuclear neutrophils (PMN) can affect sperm motility and to assess the capacity of seminal plasma and of scavengers of reactive oxygen species to prevent any loss of motility. Blood PMN were isolated, and their capacity to generate reactive oxygen species was investigated. The effect of activated PMN was tested on the motility of Percoll-washed spermatozoa in the presence and absence of reactive oxygen species scavengers or seminal plasma (whole or fractionated). Fertile volunteers and patients attending the Infertility Clinic at the Royal Victoria Hospital. The production of reactive oxygen species by activated PMN occurred in the 1st hour after stimulation and was linearly correlated with the concentration of PMN. Percoll-washed spermatozoa had reduced motility in the presence of PMN, and the drop in motility was more severe as the concentration of PMN was increased. Catalase and dimethylsulfoxide reduced the toxic effect of PMN on sperm motility, whereas superoxide dismutase was without effect. Seminal plasma (50%, vol/vol) allowed a highly variable protective effect against the loss of sperm motility that appeared to originate predominantly from the low molecular weight (< 10 kd) fraction but also from the high molecular weight (> 12 kd) fraction of seminal plasma. These data suggest that [1] the presence of PMN, even at 0.6 x 10(6) cells/mL, in semen can be hazardous for spermatozoa, [2] H2O2 and .OH are responsible for the loss of motility, and [3H] seminal plasma confers a variable protection due to high and low molecular weight factors.