IL21R and infection: Equal numbers of WT and IL-21R−/− TB10Rg CD8+ T cells were transferred into recipient mice 7 days after low-dose aerosol M. tuberculosis infection, and the ratio of WT and IL-21R−/− TB10Rg CD8+ T cells was measured on days 8, 11, 13, and 15 post infection as previously described22.