Leprosy and cell-mediated immunity.

The intradermal injection of the purified protein derivative of tuberculin into lepromatous leprosy patients leads to a local cell-mediated immune response and to the extensive destruction of Mycobacterium leprae. This local response also occurs after intradermal injection of recombinant human interleukin-2; when administered over an 8-day period interleukin-2 evokes a systemic cell-mediated immune response and a reduction in the bacillary burden.