[Responsiveness of lymphocytes from patients with M. avium-intracellulare complex (MAC) infection to PPDs as measured by IFN-gamma production].

We investigated the responsiveness of peripheral blood lymphocytes (PBLs) from patients with M. avium-intracellulare complex (MAC) infection to the stimulation with PPDs by measuring their IFN-gamma producing ability. PBLs were obtained from MAC patients at active stage (culture-positive after three-month chemotherapy), those at inactive stage (culture-negative for three months after or during chemotherapy), and healthy donors. PPDs used were PPD-S prepared from M. tuberculosis, PPD-B from M. intracellulare, and PPD-Y from M. kansasii. PBLs from active MAC patients did not produce IFN-gamma to a significant extent by stimulation with any of three PPDs, while PBLs from inactive MAC patients showed higher responses to each PPD compared to those from active patients. In inactive MAC patients, the maximal response was observed to PPD-B among three PPDs. On the other hand, PBLs from healthy controls produced different levels of IFN-gamma in response to three different PPDs, and their response was most remarkable to PPD-S. These results indicated that the responsiveness of patients' PBLs to PPDs was impaired during active stage of MAC infection and restored on recovery from the disease.