Presence and subcellular localizations of surfactant proteins A and D in human spermatozoa

ObjectiveTo investigate the presence of surfactant protein-A (SP-A); molecular weight 34 kDa and surfactant protein-D (SP-D); and molecular weight 43 kDa in human spermatozoa.DesignProspective, research study.SettingTwo universities in Turkey.Patient(s)Semen specimens (n = 10) were obtained from normozoospermic donors.Intervention(s)Human sperm were exposed to an anti–human SP-A polyclonal antibody, and monoclonal antibody, to human SP-D protein.Main Outcome Measure(s)Presence of SP-A and SP-D proteins in human beings.Result(s)Indirect immunofluorescence assays of human sperm indicated the presence of SP-A in the mid piece, the tail, and sometimes at the equatorial region of spermatozoa. A brilliant green light detected SP-D in the tails and acrosome of some sperm. The anti–SP-A antibody detected a single band corresponding to the molecular weight values of 34 kDa in spermatozoa, whereas no band was observed in the negative control. The anti–SP-D antibody showed the expected band at 43 kDa in spermatozoa.Conclusion(s)This is the first report and a novel finding of the presence of surfactant glycoproteins on human spermatozoa.