Antibody‐induced destruction of colon antigen‐coated chicken erythrocytes by normal human lymphocytes

Abstract 51 Cr‐labeled chicken erythrocytes were sensitized with a polysaccharide antigen from colon of germ‐free rats. When exposed to highly purified human blood lymphocytes in excess (25 lymphocytes: 1 erythrocyte) in the presence of heat inactivated rabbit antiserum to rat colon antigen, the modified red cells were lysed within 16–20 h. Lysis was specific and could be inhibited by addition of increasing amounts of soluble colon antigen. Maximal lysis was induced by antibodies from hyperimmune rabbits. While antibodies of the IgG class were active in this test, IgM antibodies lacked the capacity to induce lymphocyte mediated lysis. Under the experimental conditions applied, as little as 1 ng IgG antibody was required for 50 % lysis. This corresponded to ∼ 80 000 antibody molecules for lysis of one erythrocyte. The model system described should provide a basis for further studies of the cytotoxic potential of lymphocytes and/or antibodies to colon from patients with ulcerative colitis.