Dedicator of cytokinesis 8-deficient CD4 + T cells are biased to a T H 2 effector fate at the expense of T H 1 and T H 17 cells.

Background: Dedicator of cytokinesis 8 (DOCK8) deficiency is a combined immunodeficiency caused by autosomal recessive loss-of-function mutations in DOCK8. This disorder is characterized by recurrent cutaneous infections, increased serum IgE levels, and severe atopic disease, including food-induced anaphylaxis. However, the contribution of defects in CD4 ⁺ T cells to disease pathogenesis in these patients has not been thoroughly investigated.
Objective: We sought to investigate the phenotype and function of DOCK8-deficient CD4 ⁺ T cells to determine (1) intrinsic and extrinsic CD4 ⁺ T-cell defects and (2) how defects account for the clinical features of DOCK8 deficiency.
Methods: We performed in-depth analysis of the CD4 ⁺ T-cell compartment of DOCK8-deficient patients. We enumerated subsets of CD4 ⁺ T helper cells and assessed cytokine production and transcription factor expression. Finally, we determined the levels of IgE specific for staple foods and house dust mite allergens in DOCK8-deficient patients and healthy control subjects.
Results: DOCK8-deficient memory CD4 ⁺ T cells were biased toward a T _H 2 type, and this was at the expense of T _H 1 and T _H 17 cells. In vitro polarization of DOCK8-deficient naive CD4 ⁺ T cells revealed the T _H 2 bias and T _H 17 defect to be T-cell intrinsic. Examination of allergen-specific IgE revealed plasma IgE from DOCK8-deficient patients is directed against staple food antigens but not house dust mites.
Conclusion: Investigations into the DOCK8-deficient CD4 ⁺ T cells provided an explanation for some of the clinical features of this disorder: the T _H 2 bias is likely to contribute to atopic disease, whereas defects in T _H 1 and T _H 17 cells compromise antiviral and antifungal immunity, respectively, explaining the infectious susceptibility of DOCK8-deficient patients.
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