A revacinação com a BCG modula a produção de citocinas frente a antígenos do Mycobacterium leprae, em contatos menores de 15 anos de pacientes com hanseníase

Abstract

Studies in different populations have shown that vaccination with BCG provides partial protection against leprosy. However, need of boost BCG vaccination and your impact in response immune against antigens of Mycobacterium leprae is poorly understood, mainly in children who are contacts of these patients with leprosy, and constitute population of risk for illness. This study, we investigated the paper a second dose of BCG given to contacts of leprosy patients under the age of fifteen years in modulate the response imune. Blood samples of twenty five children, who received a first dose of BCG at birth, were collected immediately before and two months after BCG revaccination. Your peripheral blood mononuclear cells (PBMC) stimulated by proteins and peptides of M. leprae, were measured IFN-γ and IL-10 by an ELISA assay. Before revaccination the serum anti-PGL1 IgG and IgM isotypes were measured by ELISA assays performed with native PGL1- coated microplates, and PPD-skin reaction was measured 2 to 3 months after revaccination. The study was approved by the local Ethic Committee, number 006-08, May 7th, 2008. BCG revaccination can induces IFN-gamma and/or IL-10 production related to antigen and age, but did not correlated with PPD-skin reaction or anti-PGL1 levels. The PBMC’s production of IFN-gamma against MLT (total M. leprae antigen) after BCG was higher on children under 4 years old (N= 8, 4203,0 ± 539,2 pg/mL before BCG x 9141,0 ± 860,9 pg/mL after BCG, p=0,015, Mann-Whitney’s test). Children between 5 and 9 years old showed an increase either of IFN-gama levels (N=11, 4912 ± 1065 pg/mL x 9249,0 ± 1171 pg/mL, p=0,024, Mann-Whitney’s test) or IL-10 levels (N=11, 210,6 ± 39,4 pg/mL x 680,3 ± 76,74 pg/mL, p=0, 0,001, Mann-Whitney’s test). However children between 10 and 15 years old failed to increase the cytokines levels after BCG booster. Contacts of multibacillary patients produced higher IFN-gamma levels (N= 13, 4536,0 ± 543,1 pg/mL x 9263,0 ± 989,0 pg/mL, p=0,0012, Mann-Whitney’s test) and IL-10 levels (N= 13, 235,9 ± 46,5 pg/mL x 743,5 ± 87,8, p=0,0012, Mann-Whitney’s test) against MLT after BCG, but only IFN-gamma levels (N=12, 4975,0 ± 995,8 pg/mL x 8126,0 ± 788,6, p=0,0342, Mann-Whitney’s test) increased after BCG on contacts of paucibacillary patients. The production of IFN-gamma and IL-10 against two synthetic peptides (p38 and p67), before and after BCG vaccine, were similar as seen with MLT antigen, but the absence of cytokine production against p69 help to identify this peptide as a effective diagnostic marker.