Background:Leprosy is a chronic infectious disease classified into two subgroups for therapeutic purposes:pauci-bacillary(PB)and multibacillary(MB),closely related to the host immune responses.In this context it is noteworthy looking for immunological biomarkers applicable as complementary diagnostic tools as well as a laboratorial strategy to follow-up leprosy household contacts.rnMethods:The cross-sectional study enrolled 49 participants,including 19 patients and 30 healthy controls.Periph-eral blood mononuclear cells(PBMC)were isolated and incubated in the presence of Mycobacterium leprae bacilli.The cells were prepared for surface(CD4+and CD8+)and intracytoplasmic cytokine staining(IFN-γ,IL-4 and IL-10).Multiple comparisons amongst groups were carried out by ANOVA,Kruskal-Wallis,Student Tor Mann-Whitney test.Comparative analysis of categorical variables was performed by Chi-square.Functional biomarker signature analysis was conducted using the global median values for each biomarker index as the cut-off edge to identify the propor-tion of subjects with high biomarker levels.rnResults:The cytokine signature analysis demonstrated that leprosy patients presented a polyfunctional profile of T-cells subsets,with increased frequency of IFN-γ+T-cell subsets along with IL-10+and IL-4+from CD4+T-cells,as compared to health Controls(Venn diagram report).Moreover,statistical analysis was carried out using parametric or non-parametric variance analysis followed by pairwise multiple comparisons,according to the data normality distribution.L(PB)displayed a polyfunctional profile characterized by enhanced percentage of IFN-γ+,IL-10+and IL-4+produced by most T-cell subsets,as compared to L(MB)that presented a more restricted cytokine functional profile mediated by IL-10+and IL-4+T-cells with minor contribution of IFN-γproduced by CD4+T-cells.Noteworthy was that HHC(MB)exhibited enhanced frequency of IFN-γ+T-cells,contrasting with HHC(PB)that presented a cytokine profile limited to IL-10 and IL-4.rnConclusions:Our data demonstrated that L(PB)displayed enhanced percentage of IFN-y+,IL-10+and IL-4+as compared to L(MB)that presented functional profile mediated by IL-10+and IL-4+T-cells and HHC(MB)exhibited enhanced frequency of IFN-γ+T-cells,contrasting with HHC(PB).Together,our findings provide additional immu-nological features associated with leprosy and household contacts.These data provide evidence that biomarkers of immune response can be useful complementary diagnostic/prognostic tools as well as insights that household contacts should be monitored to access putative subclinical infection.