title: Increased antimycobacterial immunity in interleukin-10-deficient mice.
abstract: Macrophage effector functions are essential for clearing mycobacterial infections. Interleukin 10 (IL-10) negatively regulates macrophages and could be a factor inhibiting effective antimycobacterial immunity. We previously showed that transgenic mice which produce excess IL-10 from T cells are susceptible to infection, even though these mice continue to produce gamma interferon (IFN-gamma) at levels similar to those in controls. Here, we extend our genetic analysis of the functions of IL-10 in antimycobacterial immunity by testing the hypothesis that IL-10-deficient (IL-10(-/-)) mice should be more resistant to mycobacteria than control mice. Mycobacterium bovis bacillus Calmette-Guérin-infected IL-10(-/-) mice had significantly lower bacterial burdens than control mice early in the infection. Contrary to expectations, however, IL-10(-/-) mice did not have increased levels of IFN-gamma, either from T cells or in the plasma, suggesting that other mechanisms are responsible for the increased resistance. However, macrophages from IL-10(-/-) mice produced increased levels of inflammatory cytokines, including IFN-gamma, as well as nitric oxide and prostaglandins, which could account for increased antimycobacterial immunity. Our genetic analysis revealed that IL-10 is an inhibitor of early mycobacterial clearance. The data also suggest that IL-10 negatively regulates numerous macrophage functions as well as playing a role in down-regulating the general inflammatory response, especially in conditions where an infection must be controlled through macrophage activity.
authors.affiliation: Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee 38105-2794, USA. peter.murray@stjude.org
authors.forename: P J
authors.initials: PJ
authors.lastname: Murray
authors.forename: R A
authors.initials: RA
authors.lastname: Young
mesh_terms: D000818:Animals; D016207:Cytokines / Q000097:blood / Q000276:immunology; D006098:Granulocytes / Q000276:immunology; D007113:Immunity, Innate; D007371:Interferon-gamma / Q000276:immunology; D016753:Interleukin-10 / Q000172:deficiency / Q000235:genetics / Q000276:immunology*; D008264:Macrophages / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009163:Mycobacterium bovis / Q000276:immunology*; D014376:Tuberculosis / Q000276:immunology
chemical_list: D016207:Cytokines; D016753:Interleukin-10; D007371:Interferon-gamma