[Clinico-immunological study of the patients infected with Mycobacterium avium complex (MAC)]

Lymphocyte functions of the peripheral blood in the patients infected with MAC (MAC-pts) were evaluated comparatively with age-matched normal controls by using flow cytometry. The results obtained were as follows: 1) In normal controls, the number of total lymphocytes and the proportion and number of T lymphocyte subsets significantly decreased with age. The proportion of natural killer lymphocytes significantly increased in elder controls. 2) In MAC-pts, the number of total lymphocytes and T lymphocyte subsets were significantly lower and the proportion of natural killer lymphocytes were higher respectively than normal controls. 3) The lymphocyte proliferation induced by PPD-S stimulation in vitro in MAC-pts was significantly lower than the normal controls in both age groups of 50-69 and 70-89 years old. 4) The lymphocyte proliferation induced by PPD-S stimulation in MAC-pts was increased slightly by adding recombinant IL-2 and significantly higher by depletion of monocytes. By combination of both treatments, it recovered to the level of normal controls. From these results, we suggested that the decline of lymphocyte proliferation induced by PPD-S stimulation in MAC-pts was due to the decrease of IL-2 production by antigen committed lymphocytes and suppression by monocytes. 5) Lymphocyte proliferation induced by PHA stimulation in vitro was also significantly depressed in MAC-pts as compared with normal controls.