In vivo depletion of CD4 and CD8 T lymphocytes impairs Mycobacterium w vaccine-induced protection against M. tubercolosis in mice

In the present study we sought to determine the relative role of CD4 and CD8 T cells in Mycobacterium w-induced protective immunity against tuberculosis of mice by in vivo depletion with specific monoclonal antibodies (mAb). Mice were immunized first with M. w, 4 weeks later treated with anti-CD4, anti-CD8 or a combination of both mAb and subsequently infected with M. tuberculosis H37Rv i.V. Numbers of colony-forming units in animals depleted of CD4 T cells, CD8 T cells or both T cell populations were significantly higher than those in control mice receiving irrelevant mAb or no mAb. Cytokine production by T cell subsets was also determined by culturing the cells remaining after in vivo depletion in the presence or absence of mycobacterial antigens. CD8 (CD4 depleted) T cells produced lower levels of interferon-γ than CD4 (CD8 depleted) T cells. These data suggest that both CD4 and CD8 T cells participate in resistance against tuberculosis induced by vaccination with M. w.