Murine and bovine ?? T cells enhance innate immunity against Brucella abortus infections.
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ABSTRACT: ?? T cells have been postulated to act as a first line of defense against infectious agents, particularly intracellular pathogens, representing an important link between the innate and adaptive immune responses. Human ?? T cells expand in the blood of brucellosis patients and are active against Brucella in vitro. However, the role of ?? T cells in vivo during experimental brucellosis has not been studied. Here we report TCR?(-/-) mice are more susceptible to B. abortus infection than C57BL/6 mice at one week post-infection as measured by splenic colonization and splenomegaly. An increase in TCR?? cells was observed in the spleens of B. abortus-infected C57BL/6 mice, which peaked at two weeks post-infection and occurred concomitantly with diminished brucellae. ?? T cells were the major source of IL-17 following infection and also produced IFN-?. Depletion of ?? T cells from C57BL/6, IL-17R?(-/-), and GMCSF(-/-) mice enhanced susceptibility to B. abortus infection although this susceptibility was unaltered in the mutant mice; however, when ?? T cells were depleted from IFN-?(-/-) mice, enhanced susceptibility was observed. Neutralization of ?? T cells in the absence of TNF-? did not further impair immunity. In the absence of TNF-? or ?? T cells, B. abortus-infected mice showed enhanced IFN-?, suggesting that they augmented production to compensate for the loss of ?? T cells and/or TNF-?. While the protective role of ?? T cells was TNF-?-dependent, ?? T cells were not the major source of TNF-? and activation of ?? T cells following B. abortus infection was TNF-?-independent. Additionally, bovine TCR?? cells were found to respond rapidly to B. abortus infection upon co-culture with autologous macrophages and could impair the intramacrophage replication of B. abortus via IFN-?. Collectively, these results demonstrate ?? T cells are important for early protection to B. abortus infections.
SUBMITTER: Skyberg JA
PROVIDER: S-EPMC3134454 | biostudies-other | 2011
REPOSITORIES: biostudies-other
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