Cytokine responses to Mycobacterium leprae unique proteins differentiate between Mycobacterium leprae infected and na?ve armadillos

摘要

New diagnostic tools for early detection of leprosy are necessary to help reduce its transmission and severity. M. leprae unique proteins have been used to assess differences in human T-cell responses in leprosy patients, household contacts and endemic controls. In this study, we examined the response of M. leprae-infected armadillos to a variety of M. leprae recombinant antigen candidates currently being examined for diagnostic efficacy in humans. Among recently M. leprae infected armadillos, IFN-γ expression was enhanced after stimulation of PBMC with all M. leprae recombinant proteins except for ML2283 (mean: 2·65 Relative Quantification (RQ)). The group mean stimulation index for M. leprae proteins ML0009, ML1601, ML2478 and ML2531 averaged 35·2 RQ and was significantly higher (P<0·05) than that measured among the non-infected, na?ve group (mean 6·2 RQ). Although ML0840 tended to enhance IFN-γ levels, the mean IFN-γ transcript levels of the currently experimentally inoculated group (20·1 RQ) was not significantly different statistically (P = 0·10) from the mean of the na?ve group (7·5 RQ). Also no statistically significant differences were observed in IFN-γ transcript levels between the resistant and currently experimentally inoculated group (P>0·05) or between the resistant and the na?ve group (P>0·05) after stimulation of PBMCs with all M. leprae recombinant proteins. Only low levels of TNF-α were observed across all groups after in vitro stimulation with all the antigens examined. These data suggest that armadillos can be used effectively to help identify M. leprae specific proteins that may be applied for monitoring T-cell responses in M. leprae infected hosts as their disease progresses as well as for the early diagnosis of leprosy.