Western blot analysis of humoral immune response to Leishmania donovani antigens in patients with post-kala-azar dermal leishmaniasis.

Sera from 32 Indian patients with post-kala-azar dermal leishmaniasis (PKDL) were examined for antibodies by immunoblot analysis using an antigen extract of Leishmania donovani. The study revealed that the humoral immune response in PKDL patients was quite distinct compared to that in kala-azar patients. Antibodies to 3 antigens of L. donovani (molecular sizes 110, 65 and 38-42 kDa) were predominant in a majority (78%) of PKDL patients. The most important finding was the consistent recognition of 2 parasite antigens (of 110 and 65 kDa) by PKDL sera; antibodies to the 110-kDa antigen were detectable in 97% of cases, while antibodies to the 65-kDa antigen were detectable in 100% of cases that were examined. None of the 18 cases of leprosy, 10 of vitiligo, or the 30 healthy persons included in the study showed antibodies to these 2 antigens. Thus Western blot analysis provided a highly sensitive test for PKDL patients. Further, it led to the identification of 2 parasite antigens (110 and 65 kDa) that elicit an antibody response in 97-100% of PKDL patients. Purified or recombinant versions of these proteins deserve consideration as potential target antigens in development of simpler, highly specific and sensitive serodiagnostic tests for PKDL.