Differential activation of alveolar and peritoneal macrophages from BCG-vaccinated guinea pigs

SummaryWe compared the effect of BCG vaccination on the mRNA expression of two prototypic cytokines, IL-12 (Type 1) and IL-10 (Type 2), in guinea pig resident alveolar macrophages (AM) or resident peritoneal macrophages (PM). Cells were stimulated with live or heat-killed Mycobacterium tuberculosis, and/or with recombinant guinea pig (rgp) TNF-α and/or rgp IFN-γ. AM from BCG-vaccinated guinea pigs expressed significantly less IL-10 mRNA and more IL-12p40 mRNA compared to AM from naive animals following stimulation with heat-killed mycobacteria. In PM from BCG-vaccinated guinea pigs, IL-12p40 mRNA was significantly up-regulated; however, the level of IL-10 mRNA was not affected by prior vaccination. rgp TNF-α or rgp IFN-γ, both alone and together, induced a significant increase of H2O2 production in PM from BCG-vaccinated animals. MHC class II expression was dramatically up-regulated in PM from BCG-vaccinated animals stimulated with both rgp TNF-α and rgp IFN-γ. The levels of IL-10 and IL-12p40 mRNA were significantly enhanced in PM stimulated with combinations of rgp TNF-α and rgp IFN-γ, and those cells suppressed the intracellular accumulation of viable, virulent M. tuberculosis. BCG vaccination results in the differential activation of guinea pig AM and PM to promote a Type 1 cytokine milieu and control intracellular mycobacteria.