Identification of a transforming growth factor alpha-like molecule in human seminal plasma*†

OBJECTIVE: To characterize the putative seminal growth promoting factor serendipitously observed when human seminal plasma was analyzed for bioactive FSH. DESIGN: A pool of human seminal plasma was subjected to sequential Sephadex G-75 (superfine) chromatography and high-performance size exclusion liquid chromatography. The fractions were tested for mitogenic activity using a rat granulosa cell assay and normal rat kidney (NRK) cells. Properties of the factor were established and characterization by gel electrophoresis and neutralization with antibody were accomplished. SETTING: Reproductive Biology Research Laboratory at McMaster University Medical Centre. MAIN OUTCOME MEASURES: Ability of purified fractions of human seminal plasma to augment the uptake of tritiated thymidine into cell DNA. RESULTS: Mitogenic activity of human seminal plasma was augmented in the presence of FSH but not hCG, PRL, E2, T, P, or dihydrotestosterone. The putative growth factor synergized with insulin-like growth factor I (IGF-I), epidermal growth factor (EGF), and transforming growth factor beta (TGF-beta) but not with TGF-alpha. Mitogenic activity was neutralized by a specific TGF-alpha antibody in a dose-dependent manner. The molecular weight of the factor as assessed by gel electrophoresis is 6 kd. CONCLUSIONS: Human seminal plasma contains a mitogen that is similar to TGF-alpha.