Inflammatory response following intranasal infection with Mycobacterium avium complex: role of T-cell subsets and gamma interferon.
The role of CD4+ and CD8+ T cells in the response to intranasal infection with a Mycobacterium avium complex isolate (MAC) was investigated. Depletion of CD4+ T cells by injected antibody exacerbated infection in the lung, spleen, and liver. There were decreased numbers of inflammatory cells in the lungs of CD4-depleted mice and a significant decrease in lung cytotoxic activity. The neutrophil response was unaffected, and in CD4-depleted mice, unlike intact infected mice, these cells were found with large numbers of associated MAC. Purified CD4+ splenic T cells produced gamma interferon (IFN-gamma) in vitro in response to MAC antigen. IFN-gamma production by cultured spleen, lung, or mediastinal lymph node cells was markedly reduced in CD4-depleted mice. In contrast, CD8+ T cells did not produce IFN-gamma in vitro, and depletion of CD8+ T cells from infected mice had no effect on bacterial growth or lung cell activation. Depletion of IFN-gamma by injected monoclonal antibody had effects similar to those of CD4 depletion, namely, exacerbation of infection and decreased lung cell cytotoxicity. We conclude that CD4+ T cells are the main T cells involved in the lung response to MAC infection and that this response is at least partially dependent on the production of IFN-gamma.
Saunders
B M
BM
Department of Microbiology, University of Melbourne, Parkville, Victoria, Australia.
Cheers
C
C
D000818:Animals; D007249:Inflammation / Q000473:pathology*; D007371:Interferon-gamma / Q000502:physiology*; D008168:Lung / Q000473:pathology*; D008264:Macrophages / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009000:Monocytes / Q000473:pathology; D009162:Mycobacterium avium / Q000276:immunology*; D009504:Neutrophils / Q000473:pathology; D016176:T-Lymphocyte Subsets / Q000502:physiology*; D014376:Tuberculosis / Q000276:immunology*
D007371:Interferon-gamma