CD4 and infection: However, 12 days post infection, Cd28flox/floxOx40cre/+ mice had reduced numbers of CXCR5+Bcl-6+CD4+ Tfh cells (Figure 2D) and IFNγ+CD44highCD4+ Th1 cells (Figure 2E) in the medLN and Th1 cells in the lungs (Figure 2F) compared to control mice.