REDUCTION OF EPIDERMAL-CELL PROLIFERATION IN SKIN-LESIONS IN LEPROMATOUS LEPROSY IS GREATER-THAN IN INDETERMINATE AND TUBERCULOID LEPROSY LESIONS

We have compared epidermal cell proliferation in skin biopsies from ar eas with lesions to contralateral areas without lesions in patients wi th indeterminate, tuberculoid and lepromatous leprosy. Cell proliferat ion was determined as the percentage of labeled cells in the basal and suprabasal epidermal layers, using autoradiographic preparations of s kin biopsies taken 1 hr after a H-3-thymidine intradermal injection. W e have found a significant reduction in epidermal cell proliferation i n areas with lesions in the three groups of patients. The greatest red uction occurred in lepromatous patients. In lesions of patients with i ndeterminate or tuberculoid leprosy, the reduction was the same, and i n both groups it was smaller than in lepromatous patients. In the area s without lesions, the index of labeled cells was similar to that of ' 'normal'' skin of nonleprosy patients. In the contralateral unaffected areas from leprosy patients and in ''normal'' skin from nonleprosy pa tients, as well as in affected areas from patients with indeterminate leprosy, epidermal cell labeling was greater in the suprabasal layer t han in the basal layer. In lesions of lepromatous patients, cell label ing was greater in the basal layer than in the suprababal layer. Our f indings suggest that the reduction of epidermal cell proliferation in leprosy patients is restricted to the cell-mediated immune response, m ore intense in lepromatous leprosy. It does not seem to be related to denervation, which is greater in tuberculoid leprosy.