IL6 and tuberculosis: In addition, the suppression of IFN-γ production in spleen cells observed with IL-6 blockade may also contribute to increased susceptibility to TB infection, since it has been reported that IL-6 [34] and IFN-γ inhibited the growth of Mycobacterium bovis in macrophages in vitro and that TB-infected IFN-γ KO mice and IFN-γ R mutant mice were unable to restrict the growth of TB and developed a fatal disseminated form of disease [35].