In the chronic M. tuberculosis Erdman TB model used in the present study, the diminished IFN-γ-producing CD4+ T cell response and augmented IL-10 expression in the lungs of B cell-deficient mice does not adversely affect the capacity of the infected host to control M. tuberculosis (Fig 1E), even though IFN-γ plays an important in host defense against the tubercle bacillus [48,50–52,64–66] and IL-10 can compromise anti-TB immunity [39,40]. This evidence concerns the gene CD4 and tuberculosis.