Increase in gamma interferon-secreting CD8(+), as well as CD4(+), T cells in lungs following aerosol infection with Mycobacterium tuberculosis

Although it is well established that CD4(+) T cells are required for the pr otective immune response against tuberculosis (T-B), there is some evidence , that CD8(+) 'T cells are also involved in the host response to Mycobacter ium tuberculosis. There is, however, a paucity of information on the pulmon ary CD8(+) T-cell response during infection. We therefore have compared the changes in both CD8(+) and CD4(+) T cells following aerosol infection with M tuberculosis. There was an observed delay between the peak of infection and the activated T cell response in the lung. The kinetics of CD8(+) and C D4(+) T-cell responses in the lung were identical, both peaking at week 8, 4 weeks later than the peak of cellular response in draining lymph nodes. S imilar changes in activation/memory phenotypes occurred on the pulmonary CD 8(+) and CD4(+) T cells. Following in vitro restimulation, both subsets syn thesized gamma interferon, a cytokine essential for controlling M. tubercul osis infection. Since lung CD8(+) T cells are actively expanded during aero sol M tuberculosis infection, it is important that both CD8(+) and CD4(+) T cells be targeted in the design of future TB vaccines.