Atopic dermatitis and skin diseaseSevere atopic dermatitis is characterized by selective expansion of circulating TH2/TC2 and TH22/TC22, but not TH17/TC17, cells within the skin-homing T-cell population

BackgroundPast studies of blood T-cell phenotyping in patients with atopic dermatitis (AD) have provided controversial results and were mostly performed before the identification of TH9, TH17, and TH22 T-cell populations in human subjects.ObjectiveWe sought to quantify TH1, TH2, TH9, TH17, and TH22 T-cell populations and corresponding CD8+ T-cell subsets in both cutaneous lymphocyte antigen (CLA)-positive and CLA− T-cell subsets in patients with AD and control subjects.MethodsWe studied 42 adults with severe AD (mean SCORAD score, 65) and 25 healthy subjects using an 11-color flow cytometric antibody panel. Frequencies of IFN-γ-, IL-22-, IL-13-, IL-17-, and IL-9-producing CD4+ and CD8+ T cells were compared in CLA− and CLA+ populations.ResultsWe measured increased TH2/TC2/IL-13+ and TH22/TC22/IL-22+ populations (P < .1) in patients with severe AD versus control subjects, with significant differences in CLA+ T-cell numbers (P < .01). A significantly lower frequency of CLA+ IFN-γ-producing cells was observed in patients with AD, with no significant differences in CLA− T-cell numbers. The CLA+ TH1/TH2 and TC1/TC2 ratio was highly imbalanced in patients with AD (10 vs 3 [P = .005] and 19 vs 7 [P < .001], respectively). Positive correlations were found between frequencies of IL-13- and IL-22-producing CD4+ and CD8+ T cells (r = 0.5 and 0.8, respectively; P < .0001), and frequencies of IL-13-producing CLA+ cells were also correlated with IgE levels and SCORAD scores. Patients with AD with skin infections had higher CD4+ IL-22+ and IL-17+ cell frequencies, which were highly significant among CLA− cells (IL-22: 3.7 vs 1.7 [P < .001] and IL-17: 1.7 vs 0.6 [P < .001]), with less significant effects among CLA+ T cells (IL-22: 11 vs 7.5, P = .04).ConclusionsSevere AD is accompanied by expansion of skin-homing TH2/TC2 and TH22/TC22 subsets with lower TH1/TC1 frequencies. These data create a critical basis for studying alterations in immune activation in adults and pediatric patients with AD.