EFFECTS OF TREATMENT ON THE HISTOPATHOLOGY OF LEPROSY

Aims-To identify the histological changes in leprosy skin lesions over the first few weeks after the start of leprosy treatment and to exami ne their relationship to reversal reaction. Methods-Sequential skin bi opsy during treatment with multiple drug therapy. In this study, a ser ies of 28 patients was studied, from whom two or more biopsies were ta ken at two week intervals. Fourteen patients had paucibacillary lepros y (PBL) and 13 had multibacillary leprosy (MBL). Results-In most cases , granuloma fraction and bacterial index fell during treatment, the ba cterial index being less sensitive than the granuloma fraction. Since the biopsies were fixed in buffered formalin and processed through to paraffin wax, little immunohistochemistry was feasible. However, there was strong evidence of immune activation, with increased expression o f HLA-DR in the granulomas of MBL and PBL cases: the epidermis also ex pressed HLA-DR in several patients. Such changes may reflect gamma IFN production from granuloma lymphocytes. Patients with reversal reactio n often showed HLA-DR expression on admission which decreased with cor ticosteroid treatment. Conclusions-The results suggest that activation of cell mediated immunity in leprosy lesions occurs during treatment with multiple drug therapy and may not be restricted to those with cli nical evidence of reversal reaction.