title: Enhancement of murine T cell I-J expression by limited proteolysis.
abstract: I-J-encoded structures on peripheral T cells and thymocytes appear normally to be blocked or shielded by material that is susceptible to proteolysis. Limited proteolysis with trypsin, papain, pronase, or chymotrypsin increased the number of peripheral T cells and thymocytes lysed by anti-I-Jk serum and complement. Proteolysis did not induce I-Jk expression on B cells or on negative strain T cells. Increased lysis was enzyme concentration and time dependent and was not due to increased susceptibility of protease-treated cells to lysis by antibody plus complement; proteolysis rendered T cells and thymocytes less susceptible to lysis by anti-H-2Kk, anti-H-2Dd, and anti-Lyt-2 antibodies. Absorption experiments showed that I-Jk determinant density was increased in the protease-treated T cell population. The I-Jk determinants detected are proteins or glycoproteins; extended proteolysis removed these molecules from the T cell surface. Treatment of T cells or thymocytes with activated macrophage culture supernatant containing proteolytic activity produced a small but reproducible increase in I-Jk expression. Proteolysis of lymphocyte membranes, possibly mediated by macrophages, may have a role in cellular differentiation and immune activation.
mesh_terms: D000818:Animals; D000961:Antilymphocyte Serum / Q000494:pharmacology; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003165:Complement System Proteins / Q000502:physiology; D006168:Guinea Pigs; D000949:Histocompatibility Antigens Class II / Q000032:analysis*; D006868:Hydrolysis; D008262:Macrophage Activation; D008264:Macrophages / Q000201:enzymology; D051379:Mice; D010447:Peptide Hydrolases / Q000494:pharmacology*; D011480:Protease Inhibitors / Q000494:pharmacology; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism
chemical_list: D000961:Antilymphocyte Serum; D000949:Histocompatibility Antigens Class II; D011480:Protease Inhibitors; D003165:Complement System Proteins; D010447:Peptide Hydrolases