Immunoregulation in infection caused by Mycobacterium tuberculosis: the presence of suppressor monocytes and the alteration of subpopulations of T lymphocytes.

This study was designed to characterize qualitative and quantitative alterations, occurring before and during chemotherapy, in the mononuclear cells of patients with infections caused by Mycobacterium tuberculosis. A hemolytic plaque-forming (PFC) assay indicated that the production of antibody to sheep red blood cells by pokeweed mitogen (PWM)-stimulated lymphocytes was suppressed in treated and untreated patients as compared with that in normal adult donors (P less than 0.001). The removal of adherent cells from the suspensions of mononuclear cells significantly enhanced the responses to the PFC assay for both the untreated (P less than 0.01) and treated (P less than 0.05) patients. Mononuclear cells from patients with tuberculosis, however, did not suppress the PFC responses of allogeneic normal mononuclear cells (P greater than 0.02). Thymus-derived (T) lymphocytes were proportionally reduced in untreated subjects (P less than 0.001) but returned to normal levels after four to six weeks of therapy (P greater than 0.2). Both groups of patients had a consistent reduction in the absolute number of circulating T cells. However, untreated patients had a relative increase in the percentage of TG cells (the subpopulation of T cells with receptors for the Fc portion of IgG) (P less than 0.001) and a concomitant decrease in TM cells (the subpopulation with Fc receptors for IgM) (P less than 0.05). These alterations in the subsets of T cells were reversed after four to six weeks of therapy.