DC Subsets in BCG Infection Figure 7. Effects of different DC subsets adoptive transfer on Th1-related cytokine production by recipient mice following challenge infection. A: The recipient mice (C57BL/6, n = 4/group) of i.v. adoptive transferred iCD8+ DC or iCD8- DC subsets and PBS treated control mice were challenged i.v. with BCG and sacrificed at day 21 post challenge as described in Materials and Methods. A, splenocytes were cultured at the concentration of 7.56106 cells/well using HK-BCG as stimulator. Culture supernatants were harvested at 72 h and the cytokines were measured by ELISA. B&C, lungs and livers were homogenized in 10 ml cold protein-free D-PBS and centrifuged. The cytokines levels in the lung (B) and liver (C) were measured by ELISA. Data are presented as mean6SD of each group. One representative experiment of three independent experiments is shown. *p,0.05; **, p,0.01. doi:10.1371/journal.pone.0009281.g007 iCD82 DC. So were the densities (MFI) of the expressed molecules. More importantly, iCD8+ DC predominantly produced Th1 promoting cytokine, IL-12p70 and IL-12p40 (not shown) while iCD82 DC produced higher IL-10. This is inline with a reported study showing CD82 DCs induced a Th2-type immune response, while the CD8+ DCs led to the Th1 differentiation [31]. IL-12 producing DC has been found to be powerful in generating protection against tuberculosis infection [32,33]. IFN-c is closely related to protective immunity to tuberculosis infection and is the principal macrophage-activating cytokine[34], which can stimu- late the synthesis of reactive oxygen intermediates and nitric oxide by inducing production of phagocyte oxidase and nitric oxide synthase within lysosomes. IFN-c induced production of reactive nitrogen intermediates is one of the most important mechanisms for controlling mycobacterial infections [35]. Therefore, the higher production of IL-12 by iCD8+DC and the subsequently enhanced IFN-c production induced by the adoptive transfer of this DC subset is likely the major reason for the better protection of the iCD8+DC recipients observed in the present study. In addition to modulate CD4 T cell response, we also found a significantly higher IFN-c production by CD8 T cell in the recipients of iCD8+DC. In fact, the difference in CD8 T cells for IFN-c production by the different experimental groups was even more apparent than in CD4 T cells. This finding is inline with recent reports showing an exceptional ability of CD8+DC to present exogenous antigens through a process of cross-presentation [36,37] and suggests the importance for enhancing CD8+ T cell responses in promoting host defense against mycobacterial infections. A notable characteristic of iCD82 DC observed in the present study is its dramatically higher production of IL-10 compared to that of iCD8+ DC. It has been reported that, although IL-10 knockout mice showed little difference in resistance to Mtb infection than wild-type mice[38], gene transgenic mice that overly expressed IL-10 exhibited increased reactivation of chronic PLoS ONE | www.plosone.org 9 February 2010 | Volume 5 | Issue 2 | e9281