Indeed, we also observed a significantly increased Foxp3 mRNA

expression in the colon itself, the organ most susceptible to inflammation caused by LIP. These data suggest that the autoreactive T cells from Aire−/− donors were prevented by Treg cells from causing overt autoimmunity during LIP in Aire-expressing hosts. In summary, our results show that lymphocytes that have developed in an Aire−/− animal are autoreactive, and when transferred to Aire-sufficient, find more lymphopenic hosts, duplicate some, but not all features of the autoimmune phenotype of Aire−/− animals. The recipients are rescued from overt autoimmunity, however, most likely by the normal functioning of Treg cells in the Aire-expressing hosts. Our results provide support for the importance of peripheral Aire expression in maintaining tolerance and preventing autoimmunity. This study has been supported by the Academy of Finland, Biomedicum Helsinki Foundation, Finnish Cultural Fund, Jalmari and Rauha Ahokas Foundation, Helsinki Biomedical Graduate School, Finnish Diabetes Research Foundation, Paulo Foundation, and Helsinki University Hospital funds. The authors declare no competing financial interest. E.K., M-K.L. and E.S. carried out the experiments, E.K. and T.P.A. designed PS-341 datasheet the research, E.K., A.M., H.J. and T.P.A. analysed the data, H.J., S.M. and T.P.A. supervised the work, E.K. and T.P.A. wrote the manuscript. “
“Leishmania parasites and

dendritic cell interactions (DCs) play an essential role in initiating and directing T cell responses and influence disease evolution. These interactions may vary of depending on Leishmania species and strains. To evaluate the correlation between Leishmania major (Lm) virulence and in-vitro human DC response, we compared the ability of high (HV) and low virulent (LV) Lm clones to invade, modulate cytokine production and interfere with differentiation of DCs. Clones derived from HV and LV (HVΔlmpdi and LVΔlmpdi), and deleted for the gene coding for a Lm protein disulphide isomerase (LmPDI), probably involved in parasite natural pathogenicity, were also used. Unlike LV, which fails to invade DCs in half the donors,

HV promastigotes were associated with a significant increase of the infected cells percentage and parasite burden. A significant decrease of both parameters was observed in HVΔlmpdi-infected DCs, compared to wild-type cells. Whatever Lm virulence, DC differentiation was accompanied by a significant decrease in CD1a expression. Lm clones decreased interleukin (IL)-12p70 production similarly during lipopolysaccharide (LPS)-induced maturation of DCs. LPS stimulation was associated with a weak increase in tumour necrosis factor (TNF)-α and IL-10 productions in HV-, HVΔlmpdi- and LVΔlmpdi-infected DCs. These results indicate that there is a significant variability in the capacity of Lm clones to infect human DCs which depends upon their virulence, probably involving LmPDI protein.