Mycobacterium avium-intracellulare induces interleukin-6 from human
monocytes and large granular lymphocytes
DK Blanchard, MB Michelini-Norris, CA Pearson, CS Freitag and JY Djeu
Department of Medical Microbiology and Immunology, University of South
Florida College of Medicine, Tampa 33612.
Mycobacterium avium-intracellulare (MAI) is an opportunistic pathogen
commonly found in acquired immunodeficiency syndrome patients, whose immune
systems are severely compromised. However, normal responses to this
bacterium are apparently sufficient to prevent disseminated infection
because disease is rarely found unless an immunocompromised state is
present. Because interleukin-6 (IL-6) is an inflammatory cytokine with a
multitude of activities, we investigated the potential of MAI to induce
IL-6 from normal human leukocytes. Peripheral blood mononuclear cells were
fractionated into monocytes (Mo), large granular lymphocytes (LGL), and T
cells and stimulated with bacteria. Culture supernatants were collected and
assayed for IL-6 activity by bioassay. Mo and LGL, but not T cells, were
found to release IL-6 within 12 hours of stimulation, with optimal
production occurring by 2 days of culture. Production of IL-6 from human
leukocyte subsets was confirmed by Northern blot analysis and by
neutralization of biologic function of the culture supernatants with
specific antisera. Taken together, these results indicate that production
of IL-6 is a key response of Mo and LGL to MAI. The role of IL-6 in MAI
infection, therefore, needs to be further investigated.
Volume 77,
Issue 10,
pp. 2218-2224,
05/15/1991
Copyright © 1991 by The American Society of Hematology
