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

Abstract

Background: 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).

Methods: 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.

Results: 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.

Conclusions: 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.

Keywords: Lymphocyte subsets; Pleural tuberculoma; T lymphocyte activation; Tregs.