SIRPA and infection: During infection by the intestinal pathogen Citrobacter rodentium, SIRPα mt mice also showed defective induction of TH17 cells in the MLNs, as well as a trend toward reduced proportions of CD4+ T cells producing IL-22 in the colonic LP, where there was a ∼40% reduction compared with the levels in WT colon (Fig.4C and D, and Supporting Information Fig. 2C).