IFNG and infection: However, correlating with our data in the i.p. infection model, at the peak of the T cell response (day 8), we observed markedly reduced numbers of total activated (CD44hi) and B8R20–27/kb-reactive CD8+ T cells in the lung (Figure 8A) and spleen (Figure 8B) of Bcl11b−/− Cko mice compared with WT mice, and the IFN-γ response in both tissues was dramatically reduced (Figure 8C).