The role of interleukin-2 (IL-2) in the specific unresponsiveness of lepromatous leprosy to Mycobacterium leprae: studies in vitro and in vivo.

The role of IL-2 in the immunological deficiency of lepromatous leprosy patients towards Mycobacterium leprae have been studied further. After initial stimulation with M. leprae + IL-2, lepromatous lymphocytes could be restimulated with M. leprae alone. The specificity of the responses obtained varied. Some patients gave a stronger response to BCG as compared to M. leprae, while in others a stronger response to M. leprae as compared to BCG was obtained. Studies of the composition of lymphocytes in dermal infiltrates subsequent to injection of killed M. leprae revealed that in both tuberculoid and lepromatous patients, early accumulation of cell staining for both IL-2 receptor and IL-2 were seen. However, with time IL-2 receptor and IL-2 staining lymphocytes diminished in lepromatous infiltrates, while these were maintained in tuberculoid lesions.