Purification and Characterization of a Pregnancy‐Associated Protein: TJ6s

PROBLEM: Characterization of the soluble form of a novel protein, TJ6 (TJ6s) with immune suppressive activity from murine fetoplacental units. METHOD: Preferential ammonium sulfate precipitation, gel filtration and ion-exchange chromatography were employed to purify the protein TJ6s from murine fetoplacental units using an anti-peptide antibody as a detection tool. Biological activity of the purified protein was studied in lymphocyte proliferation assays. RESULTS: Purified TJ6s has a M(r) of approximately 18 kDa as evidenced by SDS-PAGE in both reducing and non reducing conditions. It exerted a strong anti-proliferative activity in both anti-CD3 and Con A proliferation lymphocyte proliferation assays but not in a PHA assay, suggesting that the anti-proliferative effects on T cells are exerted only on cells specifically activated directly through T cell receptor complex. CONCLUSION: The results indicate that TJ6s is a novel anti-proliferative protein that has many of the characteristics that are considered necessary for survival of the fetal allograft.