CD4 and infection: Although expressionof fbpB was maintained at high levels from day 14 to day 42post-infection, P25TCRTh1 cell stimulation in CPE85B-infected mice was only two-to five-fold higher than in mice infected with H37Rv, and decreased as infectionprogressed to chronic stage, indicating that other mechanisms, such asinhibition of antigen presentation and/or induction of regulatory T cells, existto limit the activation of CD4+ effector T cells in thelung.