TRANSFORMING GROWTH-FACTOR-BETA AS AN IMMUNOSUPPRESSIVE PROTEIN IN HUMAN SEMINAL PLASMA

PROBLEM: Human seminal plasma is known to exhibit immunosuppressive ac tivity in seminal plasma. PURPOSE: The purpose was to characterize imm unosuppressive proteins in seminal plasma. METHOD: Gel filtration frac tions of 100 to >440 kDa were identified that inhibited DNA synthesis and killing activity of interleukin-2 stimulated lymphocytes. RESULTS: The fractions exhibiting immunosuppression also inhibited DNA synthes is in a mink lung cell bioassay commonly used to measure the activity for transforming growth factor beta (TGF-beta). The negative growth ac tivity was diminished by a TGF-beta neutralizing monoclonal antibody. TGF-beta was further detected in the active fractions by Western immun oblot. CONCLUSIONS: These results identified TGF-beta as an immunosupp ressive protein in human seminal plasma and may provide insight into t he role of immunosuppression played by seminal plasma, such as in repr oduction and neoplasia.