Role of Regulatory T Cells in Tubercular Uveitis

<p><i>Purpose</i>: To study the role of regulatory T cells (Tregs) in patients with tubercular uveitis.</p> <p><i>Methods</i>: Frequencies of peripheral Tregs, Th1, Th17 cells, and intracellular cytokines were determined in 17 tubercular uveitis patients and 18 disease controls. Function of Tregs, Th1, and Th17 cells was assessed <i>in vitro</i>. Simultaneously, ocular levels of IFN-γ, IL-17A, IL-4, and IL-10 were also measured.</p> <p><i>Results</i>: Frequencies of peripheral Tregs in tubercular uveitis subjects were significantly lower compared with disease controls. Furthermore, expression of TGF-β and IL-2Rα, but not CTLA4, was reduced in Tregs of the tubercular uveitis group. The tubercular uveitis group demonstrated heightened Th1, Th17 responses following <i>in vitro</i> stimulation with phorbol myristate acetate (PMA)/ionomycin. Interestingly, Treg suppression assay did not show a significant difference between the two groups. Ocular levels of IFN-γ, IL-17A, and IL-10 were also elevated in tubercular uveitis group.</p> <p><i>Conclusions</i>: Low Treg frequency and hyporesponsive function contribute to proinflammatory responses manifesting at ocular level in tubercular uveitis.</p