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

BAEZ N AND ; CERBÁN F; SAVID FRONTERA C ; RODRIGUEZ GALÁN MARIA CECILIA

Buenos Aires

Congreso; IV LASID meeting-LXIII Argentinean Society for Immunology Meeting - II French-Argentinean Immunology Meeting; 2015

Sociedad Argentina de Inmunología

Our previous workdemonstrated that during the acute stage of certain infections (Trypanosoma cruzi or Candida albicans) with a strong Th1component, there is an increase in CD8+CD44hi T cells inthe thymus. Our flow cytometry data demonstrated that these cells express TCRab, CD122 and the transcription factor Eomesodermin(EOMES) but not Tbet. They produce high levels of IFNg andproliferate in the presence of IL-15. These characteristics correlate with a recentlydescribed phenotype of CD8+ T cells that develop in the thymus called?Innate T cells?. The appearance of these cells in the thymus is mediated bythe inflammatory process itself and not by the pathogens since we observesimilar data when we induce systemic expression of IL-12 and IL-18 byhydrodynamic injection of their cDNAs. As for T. cruzi infection, our recent studies demonstrated that theparasite is able to infect the thymus, then both CD8+ antigen-specificand innate T cells are found simultaneously in this organ (inmunofluorescenceand flow cytometer data using specific tetramers). Interestingly, ourpreliminary data indicate that when mice are adoptively transferred with thymocytesfrom T. cruzi-infected mice previousto T. cruzi infection, a protectiveeffect can be observed since the overall survival is significantly increasedcompared to non-transferred control mice. Our results indicatethat under systemic infectious/inflammatory processes, thepresence of non-conventional CD8+ T cells suggests alteration in thenormal function of the thymus that may have implication in T cell output andultimately in the repertoire of T cells in secondary immune organs.