ARG1 and infection: Given that alternatively activated macrophages (measured by the gene expression of Arg1, Ym1, and Fizz1) are already present in the lungs of LysMcreSOCS3loxP/loxP mice before infection these mice appear to be constitutively permissive for Mtb. As a consequence, the hyperinflammatory phenotype of LysMcreSOCS3loxP/loxP mice may have been expedited by this initial susceptibility.