Polyfunctional T cell responses to ESAT-6 and PPD after treatment in multidrugresistant tuberculosis patients. (43.26)

Abstract Background: Treatment failure against Mycobacterium tuberculosis (Mtb) infection has contributed to the development of multidrug resistant (MDR) tuberculosis. Polyfunctional (PF)-T cells secrete IFN-γ+IL-2+TNF-α+ and mediate protective immunity during chronic infections. Objective: characterize and compared the frequency of PF T cells responding to ESAT-6 and PPD antigens. Methods: We followed 10 MDR TB patients longitudinally 3 months after anti-MDR TB treatment. All samples were obtained in accordance with the Institutional Review Board’s protocol. Peripheral blood mononuclear cells (PBMCs) were stimulated with ESAT-6 or PPD and prepared for FACS analysis of CD3, CD4, CD8, IFN-γ, TNF-α and IL-2. Results: Basal samples from all patients showed a positive response to ESAT-6 and PPD antigens; however, the frequency of CD4+ and CD8+ T cells producing any combination of cytokines was not different. The proportion of IFN-γ+TNF-α+IL-2+, IFN-γ+ and TNF-α ESAT-6 CD4+ T cells increased significantly (p=0.02) when compared with pretreatment values. When cells were stimulated with PPD, IFN-γ+TNF-α+, IFN-γ+ and TNF-α+ CD4+ T cells also increased. The frequency of triple positive ESAT-6 CD8+ T cells was not different. For both, ESAT-6 and PPD antigens IFN-γ+TNF-α+, IFN-γ+ and TNF-α+ CD8+ T cells increased significantly (p<0.001). Conclusions: Our results support that PF T cell responses are actually recovered during the first 3 months of therapy.