The role of suppressor cells in the pathogenesis of common variable hypogammaglobulinemia and the immunodeficiency associated with myeloma.

The role of suppressor cells in the pathogenesis of immunodeficiency was analyzed using a technique that permits study of the differentiation of B lymphocytes into immunoglobulin-synthesizing plasma cells. Lymphocytes from normals synthesized 4,910 ng of IgM, 1,270 ng of IgA, and 1,625 ng of IgG per 2 X 10(6) cells when cultured for 7 days in the presence of pokeweed mitogen. In contrast the lymphocytes from patients with common variable hypogammaglobulinemia did not synthesize significant quantities of immunoglobulin. When lymphocytes from 9 of 13 patients with common variable hypogammaglobulinemia studied were cocultured with normal lymphocytes, the synthesis of immunoglobulin by the normal lymphocytes was depressed by 75-100%. A comparable suppression of immunoglobulin synthesis by normal lymphocytes was observed when they were cocultured with T cells from hypogammaglobulinemic patients. These studies suggest that in some patients the disease common variable hypogammaglobulinemia may not be due to an intrinsic defect of B cells alone but may be cuased or perpetuated by an abnormality of regulatory T cells that act to suppress B-cell maturation and antibody production. Peripheral blood lymphocytes from myeloma patients also had a drastically reduced capacity to produce polyclonal immunoglobulins. Three of 6 myeloma patients tested had circulating mononuclear cells that suppressed immunoglobulin production by cocultured normal lymphocytes. Purified T cells from myeloma patients did not mediate this suppressor effect. These observations suggest that one mechanism for the humoral immune deficiency observed in myeloma patients is a block of polyclonal B-cell maturation by suppressor cells.