CD4(-CELLS CAN DESTROY AUTOLOGOUS AND MHC-MATCHED MACROPHAGES BUT FAIL TB KILL INTRACELLULAR MYCOBACTERIUM-BOVIS BCG() CYTOLYTIC T)

Mycobacterium bovis-BCG infected macrophages were exposed in vitro to PPD-stimulated T lymphocytes from tuberculin responsive donors or to a panel of mycobacterial-antigen specific CD4(+) T cell clones. Both po lyclonal and clonal T cells caused considerable antigen-specific lysis of autologous or MHC class II matched macrophages. However, lysis of infected macrophages did not significantly affect the number of viable mycobacteria which were released into the culture media from lysed ma crophages. In tuberculosis, CD4(+) cytolytic T cells may be primarily involved in tissue destruction and lack a significant role in acquired cellular immunity.