In human TB granulomas, furthermore, there is a distinct spatial distribution consisting of M1 macrophages expressing iNOS at high levels and ARG1 at low levels in the central granuloma regions containing M. tuberculosis-infected macrophages compared to peripheral granuloma regions containing M2 macrophages, which have high expression of ARG1 and low expression of iNOS (95). This evidence concerns the gene ARG1 and tuberculosis.