IL-12 and IFN-gamma in host defense against mycobacteria and salmonella inmice and men

The development of gene-knockout mice and the identification of gene-defici ent humans have improved our understanding of the role of IL-12 and IFN-gam ma in host defense. Comparison of experimental and natural infections has s hown that animals and humans genetically deficient in immunity mediated by IL-12 or IFN-gamma are highly susceptible to mycobacteria and salmonella. I mpaired secretion of, or response to,IFN-gamma is the common : pathogenic m echanism that accounts for impaired granuloma formation and uncontrolled gr owth of bacteria within macrophages. The axis formed between IL-12 and IFN- gamma is essential for protective immunity against mycobacteria and salmone lla in mice and men.