CD4⁺CD25⁺Foxp3⁺ T regulatory cells, Th1 (CCR5, IL-2, IFN-γ) and Th2 (CCR4, IL-4, Il-13) type chemokine receptors and intracellular cytokines in children with common variable immunodeficiency

Abstract

Common variable immunodeficiency (CVID) is a heterogeneous group of primary antibody deficiencies characterized by decreased serum immunoglobulin G along with a decrease in serum IgA and/or IgM, defective specific antibody production, and recurrent bacterial infections. Abnormal lymphocyte trafficking, dysregulated cellular responses to chemokines, and uncontrolled T cell polarization may be involved in the pathogenesis and may help to understand the clinical complications. We evaluated T helper cell subsets (chemokine receptors CCR4, CCR5, and CCR7), expressions on T lymphocytes, intracellular cytokines -IL-2, IL-4, IL-13, IFN-g-on CD4 + T cells, and expression of CD4 + CD25 + Foxp3 + regulatory T cells of 20 CVID patients and 26 healthy controls. Autoimmune clinical findings and other complications were also determined. Percentages and absolute numbers of CD4 + CD25 + Foxp3 + cells did not show any significant difference between CVID cases and healthy controls nor between severe and moderate disease patients. The only significant difference regarding Th1 and Th2 type intracellular cytokines was the decreased absolute numbers of CD3 + CD4 + IL4 + cells in CVID cases. There were some findings about T helper cell type dominance in CVID patients such as positive correlation between hepatomegaly and high IL-2 and IFN-g in CD3 + CD4 + cells and very high expression of CCR5 (Th1) on CD3 + CD4 + cells in patients with granuloma. Th1 (CCR5) and Th2 (CCR4) type chemokine receptors did not show any dominance in CVID cases. However, frequencies of CCR7 expressing CD3 + T cells, CD3 + CD4 + T helper cells and CD3 + CD8 + T cytotoxic cells were significantly lower in severe CVID patients. In addition, presence of autoimmune clinical findings was negatively correlated with CCR7 + cells. As CCR7 is a key mediator balancing immunity and tolerance in the immune system, the abnormality of this mediator may contribute to the profound immune dysregulation seen in CVID. In addition, Th1 cells seem to be more involved in the disease pathogenesis than Th2 cells.

T-Cell Abnormalities in Common Variable Immunodeficiency

“…In contrast, Kutukculer et al [14] recently suggested that Treg cells do not play an important role in the pathogenesis of CVID. The authors reported percentages and absolute counts of Treg cells, with no significant difference between CVID patients and healthy controls or between patients with severe disease and patients with moderate disease [14].…”

“…T H 1 cells seem to be more involved in pathogenesis than T H 2 cells. CVID patients with hepatomegaly had higher IL-2 and IFN-γ levels in stimulated CD4 + T cells, and patients with granuloma were found to have higher CCR5 expression in CD4 + T cells, suggesting that T H 1 cells may play a role in granuloma formation in CVID patients [14]. Overall, increased production of some chemokines [56] and cytokines, including IFN-γ [57], TNF-α [12], IL-12 [57], IL-9 [49], IL-4, and IL-10 [58] by T H subsets has been reported in CVID patients [59].…”

“…Moreover, residual Treg cells appear to have reduced suppressive capacity [36] with downregulation of FoxP3 protein and diminished expression of inhibitory markers such as CTLA-4 and GITR [64]. In contrast, Kutukculer et al [14] recently suggested that Treg cells do not play an important role in the pathogenesis of CVID. The authors reported percentages and absolute counts of Treg cells, with no significant difference between CVID patients and healthy controls or between patients with severe disease and patients with moderate disease [14].…”

“…However, an alteration in the frequency and function of T cells has also been demonstrated in patients with CVID [12][13][14]. The influence of these defects on the interaction between T and B cells could explain not only defective antibody production, but also the development of other complications, including recurrent bacterial and viral infections, gastrointestinal disease, lymphoma, autoimmunity, inflammation, and early-onset bronchiectasis in CVID patients [15][16][17].…”

“…Traditionally, the T-cell abnormalities that characterize CVID included a reduced T-cell count, decreased lymphocyte proliferation in response to mitogens and antigens, defective T-cell signaling, decline of regulatory T cell (Tregs) counts, uncontrolled T-cell polarization, elevated levels of T-cell activation markers, and abnormality in cytokine production secondary to gene polymorphisms [12][13][14][21][22][23][24][25][26].…”