Induction of suppressor T cells by anti-globoside antibodies in cancer sera

T cells treated with cancer sera frequently suppressed immunoglobulin production by autologous lymphocytes stimulated with pokeweed mitogen. Sera from healthy individuals did not induce suppressor activity. This suppression is not caused by TG cells (T cells bearing receptors for the Fc portion of immunoglobulin G [IgG]) interacting with immune complexes, because we used T cells depleted of TG cells. The suppressor-inducing factors were separated into an IgG-containing fraction and a fraction with a smaller molecular weight. IgG fractions from all sera that were positive for anti-globoside antibody induced suppressor T cells, and elimination of the anti-globoside antibody from these IgG fractions reduced the ability to induce suppressor T cells. T cells treated with rabbit anti-globoside antiserum also activated suppressor T cells. These observations indicate that the antibodies directed to the globoside antigen on suppressor T cells stimulate the suppressor T cells, and that anti-globoside antibody in cancer sera may play a role in causing immunodeficiency in cancer patients.