Immunoglobulin synthesis by peripheral blood mononuclear cells in minimal change nephrotic syndrome.

The spontaneous and pokeweed mitogen (PWM)-induced immunoglobulin synthesizing activities of circulating mononuclear cells (MNC) from minimal change nephrotic syndrome systemic (MCNS) patients in relapse (N = 13) were compared with those of patients in remission (N = 9), patients with active systemic lupus erythematosus (SLE, N = 9), and healthy controls (N = 17). Cumulative amounts of IgM, IgG, and IgA secreted over a 12-day culture period were determined in a solid phase radioimmunoassay. Mean levels of spontaneous immunoglobulin production in control cultures did not exceed 370 ng/ml. In contrast unstimulated IgM, IgG, and IgA synthesis among MCNS patients in relapse averaged 588, 1258, and 2665 ng/ml, respectively. The majority of patients exhibited synthetic activities that equalled or exceeded those of patients with active SLE. Spontaneous immunoglobulin production declined by 80 to 97% in three patients restudied in stable remission. A fourth patient with frequent relapses maintained high rates of synthesis in remission as well as in relapse. PWM stimulation increased immunoglobulin production in patients in remission and controls but failed to increase or suppressed immunoglobulin secretion in SLE patients and patients in relapse. These results suggest that MNC from MCNS patients in relapse are reversibly activated in vivo.