Reatividade sorológica e resposta de citocinas aos antígenos LID-1, NDO-LID e NDOHSA em pacientes com hanseníase e contatos intradomiciliares provenientes de regiões endêmicas do Rio de Janeiro e Minas Gerais.

Abstract

Leprosy is still a serious health problem in Brazil and in several regions of the world. Difficulties in leprosy diagnosis result in delayed treatment and more severe disabilities. The objective of this study was to evaluate the diagnostic potential of three M. leprae specific antigens: (i) LID-1, a fusion of the recombinant proteins ML0405 and ML2331; (ii) NDO-HSA, a conjugate formed by natural octyl disaccharide bound to human serum albumin; and, (iii) NDO-LID, a combination of LID-1 and NDO. Sera from multibacillary (MB, n=18) and paucibacillary (PB, n=20) leprosy patients and household contacts (HHC) from MB (n=28) and PB (n=20) were used to measure IgM, IgG, IgG1, IgG2, IgG3, and IgG4 responses by ELISA. We also analyzed the levels of IL-17, IFN-y, TNFα, IL-10, IL-6, IL-4 e IL-2 After PBMC stimulation with the LID-1, NDO-LID and NDOHSA antigens in MB (10) and PB (10) leprosy patients and HHC-PB (08) and HHC-MB (09). Our results show that MB patients have high titers of antibodies against the evaluated antigens in comparison to PB patients and HHC groups. IgM antibodies showed higher reactivity to NDO-HSA, while IgG reactivity was higher against LID-1. No difference in antibody reactivity was observed between the HHC-MB and HHC-PB groups, or between HHC groups and endemic controls (n = 21). Receiver operating characteristic (ROC) analysis showed that the values of the area under the curve (AUC) for IgG responses to LID-1 and NDO-LID were higher in comparison to AUC values to NDO-HSA. ROC analysis indicated sensitivity of 70% and specificity of 98% for IgM against NDO-HSA in MB patients. IgG tests against LID-1, NDO-LID and NDO-HSA showed sensitivity and specificity values of 90 and 100%, 95 and 98%, 85 and 78%, respectively, while IgG1 tests indicated sensitivity of 90, 90 and 75%, and specificity of 100, 90 and 88%, respectively. About the contribution of the cytokines in M. leprae infection, our results demonstrated that IL-17 production was significantly higher in the PB group after stimulation with the LID-1, NDO-LID and NDO-HSA antigens. In addition, stimulation with the LID-1 antigen also led to increased production of IFN, TNF and IL-2 in this same group of individuals. On the other hand, it was possible to observe that the MB group presented higher IL-6 production after stimulation with LID-1 and IL-4 after stimulation with LID and NDO-LID. These results suggest that serological tests based on the detection of IgG, IgG1 and IgM antibodies may represent useful tools in the diagnosis of leprosy, and indicates a better performance of the LID-1 and NDO-LID antigens. And that cytokine research against the antigens in question constitute good biomarkers for the characterization of the clinical forms of leprosy.