Immunological studies in cases of pulmonary Mycobacterium avium complex infection without predisposing conditions

Peripheral blood mononuclear cells (PBMCs) taken from 39 primary pulmonary MAC patients and 11 control subjects were stimulated in vitro with a protein antigen PPD-B derived from M. intracellulare. Then, the activated response of the peripheral blood lymphocytes (PBLs) and the production of interferon-gamma (IFN-gamma) and interleukin-10 (IL-10) were measured. The 39 primary pulmonary MAC patients were divided into A and B groups the former patients satisfying all of the criteria for the diagnosis of nontuberculous mycobacterial disease proposed by the American Thoracic Society, with the exception of the bacteriologic criteria, and the latter, who satisfied all without exception. The 39 patients were also divided into 3 groups according to disease severity judged from chest CT features. Severity in grades 1, 2 and 3 groups were mild, moderate and severe, respectively. We compared the activated response of PBLs and the production of IFN-gamma and IL-10 by PBMCs of the control group and each patient group. The number of lymphocytes and activated T cells and the concentration of the IFN-gamma after stimulation with PPD-B were lower in each group of primary pulmonary MAC patients than in the control group. IL-10 was significantly higher in each group of primary pulmonary MAC patients than in the control group (36.6 +/- 11.8 pg/ml), and higher in group B (131.6 +/- 14.9) than in group A (81.1 +/- 31.5). There was no significant difference in the IL-10 concentration between the grade 1, 2 and 3 groups. These results suggested that the cell-mediated immunity of primary pulmonary MAC patients was suppressed as the disease progressed, and the increased production of IL-10 was related to this suppression.