CD4 and infection: Influenza‐specific memory CD4 T‐cells in the lung drive the production of chemokines that attract innate immune cells that rapidly control viral spread.51 Similarly, IFN‐γ production by L. major‐specific CD4 Trm cells drives the recruitment of inflammatory monocytes to the infection site.15 These recruited monocytes produce nitric oxide and reactive oxygen species that are toxic to the parasite.