Frequency of Treg Cells Is Reduced in CVID Patients with Autoimmunity and Splenomegaly and Is Associated with Expanded CD21lo B Lymphocytes

Common variable immunodeficiency is a heterogeneous antibody deficiency syndrome with autoimmune and inflammatory complications in a significant proportion of patients. The study was designed to evaluate the role of T regulatory (Treg) cells in common variable immunodeficiency (CVID) patients with autoimmunity. The number and frequency of Treg cells (CD4(+), CD25(hi), Foxp3(+)) were evaluated in patients and controls, and Foxp3 expression in different subgroups of CVID patients with common clinical manifestations was compared. CVID patients had significantly fewer Treg cells than controls, and low frequency of Treg cells was associated with expansion of CD21(lo) B cells in patients. Patients with autoimmunity had significantly reduced frequency but normal numbers of regulatory T cells, whilst patients with splenomegaly had significant reduction in frequency and number of regulatory T cells. Foxp3 is useful on its own or as an adjunct to classify CVID patients although the possibility of reduction in Treg cells as a secondary phenomenon cannot be excluded.