COINFECTION OF MACROPHAGES MODULATES INTERFERON-GAMMA AND TUMOR-NECROSIS-FACTOR INDUCED ACTIVATION AGAINST INTRACELLULAR PATHOGENS

Co-infection of macrophages (Mφ) with Toxoplasma gondii and Mycobacterium avium-intracellulare complex (MAC) has been observed in patients with acquired immunodeficiency syndrome (AIDS). In this study we have demonstrated that co-infected murine Mφ respond differently to cytokine stimulation than Mφ infected with either of the microorganisms alone. Whereas treatment with interferon γ (IFN-γ) activated both single and co-infected groups of Mφ to kill T. gondii, treatment with TNF did not influence the rate of MAC growth in co-infected Mφ, in contrast with the inhibition ofgrowth observed in MAC-infected Mφ. These results suggest that in AIDS patients suffering infection with multiple intracellular pathogens, the ability of cytokines to stimulate microbicidal or static activity in mononuclear phagocytes can be impaired by the presence of more than one of the intracellular organisms. © 1990, Rockefeller University Press., All rights reserved.