Interestingly, despite the significance of IFN-γ in TB control, the diminished expression of IFN-γ-producing CD4+ T cells in the lungs of B cell-deficient μMT (Fig 3C) with chronic tuberculous infection, appears not to compromise the restriction of M. tuberculosis growth, as assessed by quantification of bacterial burden (Fig 1E). Here, CD4 is linked to tuberculosis.