Concentration-dependent effects of mycobacteria on the stimulation of murine T-cell clones.

M. leprae produced concentration-dependent bimodal effects in cultures of M. leprae-immune lymphocytes. At low to intermediate concentrations, M. leprae and other species of mycobacteria stimulated lymphoproliferation of M. Leprae T-helper cell clones, whereas at high concentrations responses were reduced. Lymphokine production by M. leprae-immune T-cell hybridomas also showed bimodal responses to different concentrations of M. leprae. These results indicate that mycobacterial antigen may directly induce tolerance of responsing lymphocytes.