EFFECT OF RHUIFN-GAMMA TREATMENT IN MULTIBACILLARY LEPROSY PATIENTS

Previous studies have shown that when multibacillary leprosy patients were treated with recombinant human interferon gamma (rhuIFN-gamma) fo r 6-10 months there was an accelerated reduction in the number of acid -fast bacilli in the skin al the site of injection as well as an accel erated bacillary reduction at distal sites. However, this favorable ou tcome of IFN-gamma treatment was associated with the development of er ythema nodosum leprosum (ENL). The present study was undertaken to inv estigate whether rhuIFN-gamma induced bacillary clearance could be dis associated from the induction of ENL. rhuIFN-gamma was administered to gether with thalidomide and conventional multidrug chemotherapy to new ly diagnosed leprosy patients. During treatment with this combination of drugs, the mean reduction in bacterial load was the same as the red uction observed with chemotherapy alone. Moreover, the inclusion of th alidomide in the treatment regimen was associated with a low frequency of ENE episodes. A second group of leprosy patients, who had already completed 2 years of chemotherapy, were treated with rhuIFN-gamma only , In those patients who were skin bacilli negative, ENL did not occur during rhuIFN-gamma treatment. In contrast, in bacilli-positive patien ts the frequency of ENL during rhuIFN-gamma treatment was higher, as w as the occurrence of local erythema and induration. However, rhuIFN-ga mma treatment without concomitant chemotherapy did not result in a red uction in the bacterial load in the skin of bacilli-positive patients. These findings, taken together, indicate that rhuIFN-gamma does not, by itself, accelerate bacterial clearance, but requires concomitant ch emotherapy to achieve the accelerated reduction in bacillary load. Tha lidomide reduces the frequency of IFN-gamma-induced ENL, but also elim inates the IFN-gamma-induced bacillary clearance.