Alterations in CD4⁺ Expression, FoxP3, and Regulatory T Cells in Iraqi Patients with Pulmonary Tuberculosis: A Case–Control Study.

Abstract

Background: Effective control of Mycobacterium tuberculosis relies on CD4⁺ T cells, whereas regulatory T cells (Tregs) restrain excessive immune responses. Changes in the balance of these cell populations may contribute to tuberculosis pathogenesis. This study aimed to assess the CD4⁺ T-cell expression and Treg frequencies in patients with active tuberculosis and compared them with those in healthy controls. Methods: Blood samples were taken from the veins of 50 patients with tuberculosis and 50 apparently healthy controls, and the percentages of CD4⁺ T cells, FoxP3 molecules, and T reg cells were assessed by Flow Cytometry. Results: Patients with active tuberculosis had a significantly higher proportion of regulatory T cells (Tregs) than healthy controls, whereas CD4⁺ T-cell expression was significantly lower in Tuberculosis patients than in controls. Conclusion: Patients with tuberculosis exhibited weaker CD4⁺ T-cell responses and higher Treg frequencies, suggesting immune dysregulation during Mycobacterium tuberculosis infection. Although elevated Tregs may help maintain immune homeostasis and limit tissue damage, they may also suppress protective antimycobacterial immunity and contribute to bacterial persistence.