Appearance of innate T cells in thymus in infectious/inflammatory conditions

BAEZ NATALIA SOLEDAD; CERBÁN FABIO; SAVID FRONTERA CONSTANZA ; RODRIGUEZ-GALÁN MARIA CECILIA

Buenos Aires

Congreso; LXIII Argentinean Immunology Society Meeting; 2015

Our previous work demonstrated that during the acute stage of certain infections (Trypanosoma cruzi or Candida albicans) with a strong Th1 component, there is an increase in CD8+CD44hi T cells in the thymus. Our flow cytometry data demonstrated that these cells express TCRCD122 and the transcription factor Eomesodermin but not Tbet. They produce high levels of IFN and proliferate in the presence of IL-15(p<0,05). These characteristics correlate with a recently described phenotype of CD8+ T cells that develop in the thymus called ?Innate T cells?. The appearance of these cells in the thymus is mediated by the inflammatory process itself and not by the pathogens since we observe similar data when we induce systemic expression of IL-12 and IL-18 by hydrodynamic injection of their cDNAs(p<0,05). As for T. cruzi infection, our recent studies demonstrated that the parasite is able to infect the thymus, then both CD8+ antigen-specific and innate T cells are found simultaneously in this organ (inmunofluorescence and flow cytometer data using specific tetramers, p<0,05).Interestingly, our preliminary data indicate that when mice are adoptively transferred with thymocytes from T. cruzi-infected mice previous to T. cruzi infection, a protective effect can be observed since the overall survival is significantly increased compared to non-transferred control mice. Our results indicate that under systemic infectious/inflammatory processes, the presence of non-conventional CD8+ T cells suggests alteration in the normal function of the thymus that may have implication in T cell output and ultimately in the repertoire of T cells in secondary immune organs.