Immunoregulatory factors derived from human tumors. II. Partial purification and further immunobiochemical characterization of a human sarcoma-derived immunosuppressive factor expressing HLA-DR and immunoglobulin-related determinants.
An immunoregulatory factor (IRF) that suppresses Con A-mediated peripheral blood mononuclear cell (PBM) proliferative responses was partially purified by DEAE anion exchange chromatography and affinity chromatography from a 3 M KCl extract of a human liposarcoma. The factor (m.w. = 70K) co-purified with albumin, monitored by two-dimensional gel electrophoresis, and demonstrated a heterogeneous isoelectric point (pI 7.6-7.8). Xenoantisera produced against the DEAE-purified fraction and coupled to Affigel 10 removed suppressive activity that could subsequently be eluted by glycine-HCl, pH 3.5. An anti-albumin column partially removed activity, but the unbound 70K factor could still be detected in the column effluent. A xenoantiserum to this 70K effluent coupled to acrylamide beads completely removed the immunosuppressive activity in immunodepletion experiments. Further direct binding enzyme-linked immunoassays (ELISA) and solid-phase immunoabsorption experiments with monoclonal antibodies to human anti-HLA-DR framework determinants and a constant region of the IgM mu-chain demonstrated determinants on the 70K factor recognized by these antibodies.
D002478:Cells, Cultured; D000939:Epitopes; D006023:Glycoproteins / Q000276:immunology; D006684:HLA-DR Antigens; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D006801:Humans; D007108:Immune Tolerance; D007136:Immunoglobulins / Q000276:immunology*; D008970:Molecular Weight; D009363:Neoplasm Proteins / Q000276:immunology / Q000302:isolation & purification; D012509:Sarcoma / Q000276:immunology*
D000939:Epitopes; D006023:Glycoproteins; D006684:HLA-DR Antigens; D000949:Histocompatibility Antigens Class II; D007136:Immunoglobulins; D009363:Neoplasm Proteins