The expression of early resistance to an infection with Mycobacterium tuberculosis by old mice is dependent on IFN type II (IFN-gamma) but not IFN type I.
Old mice can express a transient early resistance to infection with M. tuberculosis that requires the presence of CD8 T cells within the lungs. Further characterization of those CD8 T cells within the aged lung established that the majority of CD8 T cells from old mice expressed the IL-15 receptor (CD122) in combination with bright expression of CD44 (CD44(hi)), and were capable of producing IFN-gamma after T cell receptor cross-linking. It has been previously described that CD8 CD44(hi) T cells proliferate in response to IFN-I, acting via IL-15, and therefore we determined whether IFN-I signaling could be a participant in the response of CD8 T cells within the lungs of old mice infected with M. tuberculosis. We demonstrate here that IFN-I signaling was required for the expansion of CD8 T cells within the aging lung in response to infection with M. tuberculosis, but that IFN-I signaling had no influence on the capacity of old mice to express early resistance to an infection with M. tuberculosis. Resident CD8 T cells were still however capable of producing IFN-gamma, which we demonstrate here to be critical in the expression of early resistance, suggesting that the expression of early resistance requires the participation, but not expansion, of the CD8 T cell pool within the aging lung.
Turner
Joanne
J
Department of Internal Medicine, Center for Microbial Interface Biology, The Ohio State University, Columbus, OH 43210, USA. turner-11@medctr.osu.edu
Orme
Ian M
IM
D000375:Aging; D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000473:pathology; D018414:CD8-Positive T-Lymphocytes / Q000378:metabolism / Q000473:pathology; D002462:Cell Membrane / Q000378:metabolism; D004198:Disease Susceptibility; D007370:Interferon Type I / Q000378:metabolism*; D007371:Interferon-gamma / Q000096:biosynthesis / Q000172:deficiency / Q000378:metabolism*; D008168:Lung / Q000473:pathology; D008565:Membrane Proteins; D051379:Mice; D008815:Mice, Inbred Strains; D018345:Mice, Knockout; D009169:Mycobacterium tuberculosis; D053633:Receptor, Interferon alpha-beta; D017471:Receptors, Interferon / Q000172:deficiency; D015375:Receptors, Interleukin-2 / Q000378:metabolism; D014376:Tuberculosis / Q000209:etiology* / Q000378:metabolism* / Q000473:pathology
D007370:Interferon Type I; D008565:Membrane Proteins; D017471:Receptors, Interferon; D015375:Receptors, Interleukin-2; D053633:Receptor, Interferon alpha-beta; D007371:Interferon-gamma