Decreased Frequency of Regulatory T Cells in Patients with Common Variable Immunodeficiency.

Introduction: Common variable immunodeficiency disorder (CVID) is a heterogeneous syndrome, characterized by deficient antibody production and recurrent bacterial infections in addition abnormalities in T cells. CD4⁺CD25^high regulatory T cells (Treg) are essential modulators of immune responses, including down-modulation of immune response to pathogens, allergens, cancer cells and self-antigens. Objective: In this study we set out to investigate the frequency of Treg cells in CVID patients and correlate with their immune activation status. Materials and Methods: Sixteen patients (6 males and 10 females) with CVID who had been treated with regular intravenous immunoglobulin and 14 controls were enrolled. Quantitative analyses of peripheral blood mononuclear cells (PBMC) were performed by multiparametric flow cytometry using the following cell markers: CD38, HLA-DR, CCR5 (immune activation); CD4, CD25, FOXP3, CD127, and OX40 (Treg cells); Ki-67 and IFN-γ (intracellular cytokine). Results: A significantly lower proportion of CD4⁺CD25^highFOXP3 T cells was observed in CVID patients compared with healthy controls (P,0.05). In addition to a higher proportion of CD8⁺ T cells from CVID patients expressing the activation markers, CD38+ and HLA-DR+ (P,0.05), we observed no significant correlation between Tregs and immune activation. Conclusion: Our results demonstrate that a reduction in Treg cells could have impaired immune function in CVID patients. [ABSTRACT FROM AUTHOR]