Study of HLA-DR expression on skin lesions of leprosy before and during multiple drug therapy.

Leprosy is a dynamic disease in which cell mediated immunity (CMI) plays an important role in host defense and control of the clinical spectrum. This study was carried out to detect immune activation in the granuloma of leprosy during multiple drug therapy (MDT) by studying the expression of human leukocytic antigen-DR (HLA-DR) in the granuloma before and during therapy. Skin punch biopsies were taken before and at least once 2-4 weeks after starting MDT in 20 newly diagnosed patients. Two biopsies, 2-4 weeks apart, were also taken from 10 new patients who did not yet receive any treatment, for comparison. Furthermore, biopsies were taken before and during corticosteroid therapy in five patients who developed reversal reaction during MDT. The biopsy specimens were studied for the expression of HLA-DR using the immunofluorescent staining which was found to be visibly increased in 17 out of 20 new cases (85%) within 2-4 weeks after starting MDT, while no change in the expression was noticed in those who did not receive any treatment (p < 0.001). This might reflect the increased production of interferon gamma (IFN gamma) specially from granuloma lymphocytes after being stimulated with the excessive release of mycobacterial antigen from killed bacilli during therapy. The five patients who developed reversal reaction during MDT had strong HLA-DR expression in the first biopsies which declined subsequently 2-6 weeks after starting prednisolone therapy. Our results suggest that CMI was activated in skin lesions of leprosy during MDT. Such activation was not only restricted to those who developed reversal reaction across the therapeutic course, which indicates that the difference between patients who developed such reaction and those who did not, was likely to be quantitative rather than qualitative, with a more exaggerated CMI response in the former. Furthermore, it seems that the beneficial effect of MDT is accompanied by important changes in the immune cell profile which have a great role in overcoming such infection.