DNA immunization of Mycobacterium tuberculosis resuscitation-promoting factor B elicits polyfunctional CD8+ T cell responses

PURPOSE: T cell-mediated immune responses, and particularly activation of polyfunctional T cells that simultaneously produce multiple cytokines, are necessary for the control of Mycobacterium tuberculosis. In the present study, we examined if DNA immunization of Mycobacterium tuberculosis resuscitation-promoting factor B (RpfB) elicits polyfunctional T cell responses in mice. MATERIALS AND METHODS: C57BL/6 mice were immunized intramuscularly three times, at 3-week intervals, with RpfB-expressing plasmid DNA. For comparison, protein immunization was performed with recombinant RpfB in control mice. After immunization, RpfB-specific T cell responses were assessed by interferon-gamma (IFN-gamma) enzyme-linked immunosorbent spot assay and intracellular cytokine staining (ICS), and T cell polyfunctionality was assessed from the ICS data. RESULTS: RpfB DNA immunization induced not only humoral immune responses, but also CD8+ and CD4+ T cell responses. Immunodominant T-cell epitopes were identified within RpfB by assays with overlapping peptides. RpfB DNA immunization elicited a polyfunctional CD8+ T cell response that was dominated by a functional phenotype of IFN-gamma+/TNF-alpha+/IL-2-/CD107a+. CONCLUSION: RpfB DNA immunization elicits polyfunctional CD8+ T cell responses, suggesting that RpfB DNA immunization might induce protective immunity against tuberculosis.

Significant evaluation of polyfunctional T cells / 中国免疫学杂志

During the past few years,mounting evidence has proved that the protection induced by vaccines or the prognosis of diseases is correlated with the quantity and quality of T cell responses in both mouse models and human infectious diseases.Examination of one or a few effector functions might not fully reflect the antigen-specific immunity.Recent studies demonstrated that after antigen stimulation,T cells could be induced to produce two or more effector functions simultaneously at single cell level,including cytokines,chemokines production and cytotoxic related molecules,which are named as polyfunctional T cells.Further studies indicated that these polyfunctional T cells are linked to protection from infectious diseases.Therefore,measuring multiple functions of T cells simultaneously is essential for the proper evaluation of specific immunity and may have substantial implications for the design of vaccines.