Altered cytokine profiles in relapsed paucibacillary leprosy: a case report

BACKGROUND: Individuals with relapses of leprosy should be monitored carefully, however, with respect to paucibacillary (PB) leprosy, it is sometimes difficult to make a definitive diagnosis of relapse, because the bacillary index is often negative. To evaluate the usefulness of cytokine profiling in a patient with relapsed PB leprosy who tested negative for anti-phenolic glycolipid-I antibodies, we analyzed the Mycobacterium leprae protein-induced cytokine expression in peripheral blood mononuclear cells of the patient. CASE PRESENTATION: An 89-year-old-male relapsed PB patient, first treated for leprosy over 50 years prior, was examined. In April 2012, he noticed three skin lesions consisting of annular erythema in the thighs. Slit skin smear tests were negative, and skin biopsies revealed a pathology of indeterminate-to-borderline tuberculoid leprosy. He received 600 mg of rifampicin once per month and 75 mg of dapsone daily for 12 months. The annular erythemas disappeared after starting treatment. Before treatment, and 6 and 12 months after starting treatment, the Th1/Th2 cytokine profiles in the supernatant of mononuclear cells from the patient before and after stimulation with Mycobacterium leprae soluble protein (MLS) were examined using a Cytometric Bead Array (CBA) Human Th1/Th2 Cytokine Kit II. The CBA Enhanced Sensitivity Flex Set system was applied to detect small amounts of cytokines in the serum just before treatment and one year before relapse. In the culture supernatant, just before treatment, increases in IFN-γ level and the IFN-γ/IL-10 ratio and a decreased IL-6 level were observed without stimulation. Upon stimulation with MLS, just before treatment, both the IFN-γ and TNF levels increased markedly, and twelve months after starting treatment, the IFN-γ and TNF levels decreased greatly. In the serum, just before treatment, increases in IFN-γ and TNF levels and the IFN-γ/IL-10 ratio were evident compared with those measured one year before relapse. CONCLUSIONS: Cytokine profiling using culture supernatants and serum samples may be useful for the diagnosis of relapsed PB leprosy.