CXCL2 and infection: Furthermore, WT and Irg1 KO mice had comparable numbers of lung neutrophils (S9C Fig), as well as comparable mRNA expression of granulopoetic cytokines including Cxcl1, and Cxcl2, and Csf3 in the lung tissue at day 1 after M. pneumoniae infection (S9D Fig), suggesting that Irg1 deficiency may not affect neutrophil trafficking at the early stage of infection.