IL4 and infection: Infection did not exacerbate the reduction of complex I and IV enzymatic activity caused by TNFα alone or in combination with IFNγ, and IL-4 provided similar protection against the detrimental effects of this combination in the presence of infection (from −68% to −41%, P < 0.05, and −49% to −15%, P < 0.01, Fig. 6A,C).