BCG immunotherapy as an adjunct to chemotherapy in BL-LL patients – its effect on clinical regression, reaction severity, nerve function, lepromin conversion, bacterial/antigen clearance and ‘persister’ M. leprae

Abstract

Multidrug therapy in leprosy has failed to eliminate the problem of persister bacilli. Clearance of bacterial antigens is extremely slow which could predispose to continued nerve damage even after release from treatment. In the present study the immunomodulatory efficacy of BCG vaccine administered post-MDT in BL-LL leprosy patients was investigated in depth with a view to determining if augmenting chemotherapy with immunotherapy would help in faster clearance of M. leprae/antigens, bring down the level of persisters and minimise the occurrence/severity of reaction and nerve damage. This is a placebo-controlled study in treated BL-LL patients. The patients are matched with respect to age, sex, bacteriological index and history of reaction, stratified and allocated to the two groups. One group (Gr A) received two doses of BCG-MOSCOW (3-33 x 10(5) cells) and the other (Gr B) normal saline (0.85%), injected intra-dermally at 3 month intervals. The Primary outcomes assessed at the end of 6 months were bacterial/antigen clearance, lepromin conversion, granuloma clearance and the occurrence of persisters. The secondary outcomes were clinical regression, occurrence and severity of reaction and changes in nerve functions. A total of 107 BL-LL patients comprised of 49 in Gr A and 58 in Gr B; of which 36 and 42 respectively completed the study as per protocol, and are included in the final analysis. The study findings show that both the primary and the secondary out comes were comparable in the two groups. Two doses of BCG administered post-MDT (Gr A) did not significantly alter the level of persisters or help in hastening the bacterial/antigen clearance, clinical regression of lesions and granuloma clearance. Lepromin conversion rates were also comparable. While the frequency of lepra reaction/neuritis following the intervention was comparable, the severity of reactions was significantly higher in Gr A. On the positive side neural functions assessed by nerve conduction studies showed that deterioration of motor nerve conduction was significantly lower in the BCG arm. Since all patients developing moderate to severe reactions, immediately received a course of corticosteroids, it is possible that timely use of it might have helped.