Effects of cryopreservation and density-gradient washing on phospholipase C zeta concentrations in human spermatozoa

Cryopreservation and density-gradient washing (DGW) are routinely used in infertility treatment. This study used quantitative immunofluorescence analysis to report how these techniques affect concentrations of the oocyte activation factor, phospholipase C zeta (PLCζ) in spermatozoa from fertile men. DGW significantly elevated the proportion of spermatozoa in which PLCζ could be detected (by 25-81%; P < 0.0001). In contrast, in four donors, cryopreservation significantly reduced PLCζ concentrations (by 20-56%; P < 0.0001). These findings indicate that while DGW positively selects spermatozoa with detectable PLCζ, cryopreservation has significant detrimental effects upon PLCζ concentrations. Since reduced PLCζ concentrations have been implicated in deficient oocyte activation and infertility, further study is highly warranted.