Effect of 1,25 dihydroxyvitamin D3 on intracellular IFN-γ and TNF-α positive T cell subsets in pulmonary tuberculosis

We studied the immunomodulatory effect of 1,25(OH)(2)D-3 on single cell expression of IFN-gamma and TNF-alpha cytokines in T cell subsets of pulmonary tuberculosis (PTB) patients (n = 22) and normal healthy subjects (n = 22). Peripheral blood mononuclear cells (PBMCs) were cultured with live Mycobacterium tuberculosis (MTB) with or without 1,25(OH)(2)D-3 (10(-7) M) for 48 h. T cell subsets positive for IFN-gamma and TNF-alpha were enumerated by flow cytometry and the culture supernatants were assayed for both the cytokines using ELISA. In both NHS and PTB patients, a significantly reduced percentage of IFN-gamma and TNF-alpha expressing CD3+, CD3+CD4+ and CD3+CD8+ T cells were observed in cultures stimulated with live MTB and treated with 1,25(OH)(2)D-3 compared to cultures without 1,25(OH)(2)D-3 (NHS; CD3+ IFN-gamma+: p < 0.0001; CD3+TNF-alpha +: p = 0.0292 and PTB; CD3+ IFN-gamma+: p = 0.0292; CD3+ TNF-alpha +: p = 0.0028). The levels of IFN-gamma and TNF-alpha in the culture supernatants of 1,25(OH)(2)D-3 treated cultures were also found to be significantly decreased in both groups (NHS; IFN-gamma: p = 0.0001; TNF-alpha: p < 0.0001) and (PTB; IFN-gamma: p < 0.0001; TNF-alpha: p < 0.0001). A positive correlation was observed between IFN-gamma and TNF-alpha expressing CD3+CD8+ T cells in MTB stimulated cultures treated with or without 1,25(OH)(2)D-3 in NHS (p = 0.0001; p = 0.001, respectively) and PTB patients (p = 0.002; p = 0.005, respectively). The present study revealed the suppressive effect of 1,25(OH)(2)D-3 on single cell expression of IFN-gamma and TNF-alpha by CD3+CD4+ and CD3+CD8+ T cells in pulmonary tuberculosis. This suppressive effect of 1,25(OH)(2)D-3 on proinflammatory and Th1 cytokine positive cells might have a role in reducing inflammation at the site of infection. (C) 2008 Elsevier Ltd. All rights reserved.