Background Atopic dermatitis (AD) and psoriasis pathogeneses involve skin barrier impairment and immune dysregulation; however, the contribution of B-cell imbalances to these diseases has not yet been determined. Objective We sought to quantify B-cell populations and antibody-secreting cells in the blood of patients with AD, patients with psoriasis, and control subjects. Methods We studied 34 adults with moderate-to-severe AD (mean SCORAD score, 65), 24 patients with psoriasis (mean Psoriasis Area and Severity Index score, 16), and 27 healthy subjects using an 11-color flow cytometric antibody panel. IgD/CD27 and CD24/CD38 core gating systems were used to determine frequencies of plasmablasts and naive, memory, transitional, and activated B cells. Results We measured increased CD19+CD20+ B-cell counts in the skin and blood of patients with AD (P <.01). Significantly higher frequencies of chronically activated CD27+ memory and nonswitched memory B cells were observed in patients with AD (P <.05), with lower values of double-negative populations (4% for patients with AD vs 7% for patients with psoriasis [P =.001] and 6% for control subjects [P =.02]). CD23 expression was highest in patients with AD and correlated with IgE levels (P <.01) and disease severity (r = 0.6, P =.0002). Plasmablast frequencies and IgE expression were highest in all memory subsets of patients with AD (P <.01). Finally, CD19+CD24++CD38++ transitional and CD19+CD24-CD38- new memory B-cell counts were higher in patients with AD versus those in patients with psoriasis (2.8% vs 1.4% [P =.001] and 9.2% vs 5.7% [P =.02], respectively). Conclusions AD is accompanied by systemic expansion of transitional and chronically activated CD27+ memory, plasmablast, and IgE-expressing memory subsets. These data create a critical basis for the future understanding of this debilitating skin disease.
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