Measurement of vitronectin content of human spermatozoa and vitronectin concentration within seminal fluid

Objective: Vitronectin previously has been extracted from human spermatozoa and messenger RNA (mRNA) encoding vitronectin localized by reverse transcriptase in situ polymerase chain reaction (PCR) to spermatocytes of human testis. In the present experiments, we have established ranges for the content of vitronectin in living human spermatozoa and vitronectin concentration within seminal fluid of human ejaculates. Design: Seminal fluid was obtained by centrifugation and motile sperm selected by swim-up from men with normal and abnormal ejaculates, according to World Health Organization criteria, for vitronectin determinations. Setting: Academic research environment. Main Outcome Measure(s): Seminal fluid vitronectin concentrations were measured by ELISA and sperm vitronectin content by polyacrylamide gel electrophoresis and semiquantitative Western blots. Result(s): Vitronectin seminal fluid concentration was 1.35 ± 1.0 mg/mL (mean ± SD) for normospermic samples (n = 26) and 0.78 ± 0.4 mg/mL for azoospermic specimens (n = 6). Vitronectin sperm content ranged from 1 to 15 ng/10⁶ motile cells (n = 20). Both high- and low-molecular-weight material was observed. Sperm content of vitronectin did not vary with sperm morphology. Conclusion(s): These results suggest that spermatozoa represent a major source of seminal fluid vitronectin, but that a secondary source exists, perhaps through transudation from serum.