Mycobacterium bovis BCG-induced human T-cell clones from BCG-vaccinated healthy subjects: antigen specificity and lymphokine production.

A total of 121 human T-cell clones were raised from nine Mycobacterium bovis BCG-vaccinated healthy individuals. Three clones were autoreactive, 74 responded to BCG in the presence of antigen-presenting cells, and the others required in addition exogenous interleukin 2. Only one clone was CD8+ CD4-, and the rest were CD4+ CD8-. Testing with a panel of mycobacteria suggested that the clones were recognizing epitopes of varied specificity. Out of 44 clones tested, 15 were specific to BCG and Mycobacterium tuberculosis, 22 showed limited cross-reactivity, and 8 were broadly cross-reactive. None of the 22 BCG responder clones could differentiate between Danish, French, Prague, and Moreau strains of BCG. BCG and M. tuberculosis H37Rv also paralleled very closely; however, 6 of 18 BCG- and M. tuberculosis H37Rv-responding clones did not proliferate to Mycobacterium africanum. BCG- and M. tuberculosis H37Rv-specific as well as cross-reactive T-cell clones could be induced to produce interleukin 2, gamma interferon, and granulocyte-macrophage colony-stimulating factor activity.