The macrophage in tuberculosis: sinner or saint? The T cell decides

Immunity to intracellular bacteria including Mycobacterium tuberculosis crucially depends on intricate interactions between T lymphocytes and macrophages. Before contact with T lymphocytes macrophages serve as habitat for M. tuberculosis organisms; after activation by T cells they become major effectors against these pathogens. T cells comprise different subsets which express different functional activities. This paper describes evidence that different T cell subsets (CD4 alpha/beta T cells, CD8 alpha/beta T cells and gamma/delta T cells) as well as different T cell functions (interleukin secretion and target cell lysis) contribute to immunity against tuberculosis.