ATTEMPTS TO CHARACTERIZE THE MECHANISMS INVOLVED IN THE GROWTH-INHIBITION OF MYCOBACTERIUM-MICROTI IN INTERFERON-GAMMA OR TUMOR-NECROSIS-FACTOR-ALPHA ACTIVATED J774A.1 CELLS

The growth of Mycobacterium microti was inhibited within J774A.1 macro phage cells activated with either interferon-gamma or tumor necrosis f actor-alpha. Activation with interferon-gamma or tumor necrosis factor -alpha alone did not stimulate the production of nitrite in J774A.1 ce lls. Interferon-gamma but not tumor necrosis factor-alpha increased th e production of hydrogen peroxide in a concentration dependent manner but scavengers of reactive oxygen species did not influence the growth inhibiting effect of interferon-gamma within J774A.1 cells. Both inte rferon-gamma and tumor necrosis factor-alpha enhanced the fusion of M. microti containing phagosomes with lysosomes and the ultimate degrada tion of bacteria. Our results showed that growth inhibition of M. micr oti within interferon-gamma or tumor necrosis factor-alpha stimulated J774A.1 cells was independent of reactive oxygen intermediate and reac tive nitrogen intermediate production.