H5D12 MONOCLONAL-ANTIBODY IDENTIFIES A 24-KD IMMUNOSUPPRESSOR FACTOR PRODUCED BY HUMAN CHORIO CARCINOMA-CELLS

PROBLEM: The purpose of this study was to identify and characterize em bryo-associated immunosuppressor factor (EASE) secreted by chorio carc inoma cells with the help of EASF-specific monoclonal antibody H5D12 ( raised against EASF purified from embryo growth media of in vitro fert ilized human ova). METHOD: Paraffin-embedded slides of human chorio ca rcinoma as well as control cell lines were prepared, and immunohistoch emistry was done by the avidin-biotin-peroxidase technique. EASE was a ffinity purified using H5D12-Sepharose 4B from culture media of cell l ines and analyzed for immunosuppressive activity (by Concanavalin-A-in duced lymphocyte proliferation assay) and molecular weight identity (b y metabolic-labelling studies with S-35-methionine followed by immunop recipitation and SDS-PAGE). RESULTS: H5D12 showed intense immunostaini ng of BeWo chorio carcinoma cells. Biosynthetic labeling studies ident ifies this factor as a 24-kD molecule, and EASE bioassay indicates tha t this factor possesses immunosuppressive activity. No such immunosupp ressive activity or similar molecules were identified when control cel l lines were analyzed. CONCLUSIONS: Monoclonal antibody H5D12 recogniz es a 24-kD factor with immunosuppressive activity that is secreted by chorio carcinoma cells, which suggests that this is a unique factor an d may be one of the key regulators of reproductive functions.