Peripheral T cell cytokine responses for diagnosis of active tuberculosis

Abstract

Background: A test for diagnosis of active Tuberculosis (TB) from peripheral blood could tremendously improve clinical management of patients. Methods: Of 178 prospectively enrolled patients with possible TB, 60 patients were diagnosed with pulmonary and 27 patients with extrapulmonary TB. The frequencies of Mycobacterium tuberculosis (MTB) specific CD4 + T cells and CD8 + T cells producing cytokines were assessed using overnight stimulation with purified protein derivate (PPD) or early secretory antigenic target (ESAT)-6, respectively. Results: Among patients with active TB, an increased type 1 cytokine profile consisting of mainly CD4 + T cell derived interferon (IFN)-γ was detectable. Despite contributing to the cytokine profile as a whole, the independent diagnostic performance of one cytokine producing T cells as well as polyfunctional T cells was poor. IFN-γ/Interleukin(IL)-2 cytokine ratios discriminated best between active TB and other diseases. Conclusion: T cells producing one cytokine and polyfunctional T cells have a limited role in diagnosis of active TB. The significant shift from a "memory type" to an "effector type" cytokine profile may be useful for further development of a rapid immune-diagnostic tool for active TB. © 2012 Nemeth et al.