Frequency of CD4+ regulatory T cells and modulation of CD4+T lymphocyte activation in pleural tuberculoma

The expression of regulatory T cells (Tregs) is elevated in patients with active tuberculosis (TB) or multidrug-resistant TB. However, it remains uncertain whether Tregs mediate immune suppression in pleural tuberculoma (PTM).Peripheral venous blood and clinical data were collected from 56 PTM patients and 50 healthy volunteers. The expression of CD38 and HLA-DR expression in T cell subsets and Tregs was determined by flow cytometry.PTM patients had significantly more Tregs than the matched healthy controls. The expression of CD4+T cells normalized after treatment. Although the median proportions of CD3+T, CD4+T, and CD8+T lymphocytes did not differ significantly between PTM patients and healthy controls, the CD4/CD8 ratio was higher in PTM patients. Moreover, the proportion of CD4+T lymphocytes expressing activation markers, including HLA-DR and CD38, was higher in PTM patients than healthy controls. Treg expression was positively associated with the level of CD4+T lymphocyte activation.The increased expression of Tregs seen in PTM patients, and subsequent decrease after treatment, indicate that Tregs play an important role in the immune reactivity of PTM.