CD4 and infection: The results of this series of experiments revealed that at 24 weeks after infection, the frequency of BrdU+ CD4+ T cells in the lungs of B cell-deficient mice is lower than that detected in WT controls (Fig 2B and 2C; p<0.05), with a decrease of absolute number of lung BrdU+ CD4+ T cells by 45% (WT: 0.91 ± 0.07 x 105; μMT: 0.5 ± 0.09 x 105; p<0.03) (Fig 2D).