Researchers investigated the clinical and immunological characteristics of patients with alopecia areata (AA) and comorbid atopic dermatitis (AD), comparing them with patients with AA alone and AD alone.
The findings suggest that patients with both AA and AD have a distinct clinical and immunological profile, with more severe hair loss and greater type 2 immune activity than patients with AA alone.
Researchers conducted a retrospective analysis of 123 patients with alopecia areata and comorbid atopic dermatitis (AA-AD), 119 patients with non-atopic AA, and 126 patients with AD alone. Clinical data were collected between 2011 and 2024. Blood samples, plasma, and scalp tissue were also examined using flow cytometry, cytokine assays, and immunofluorescence to investigate differences in immune activity.
Compared with patients with non-atopic AA, those with AA-AD were younger, experienced more severe hair loss, and had a longer disease duration. However, their eczema was generally milder than that observed in patients with AD alone. The AA-AD group also demonstrated higher rates of dust mite allergy, elevated total immunoglobulin E (IgE), and increased eosinophil counts compared with patients with non-atopic AA.
Immunological investigations revealed increased plasma levels of IL-4, IL-6, IL-10, and IL-13 in patients with AA-AD compared with patients with non-atopic AA and healthy controls. The proportion of T helper 2 (Th2) cells and group 2 innate lymphoid cells (ILC2s) was also elevated in peripheral blood, alongside increased IL-13 production by these immune cells.
Analysis of scalp tissue further demonstrated that Th2 cells and ILC2s were more abundant in patients with AA-AD than in the comparison groups. Increased levels of these immune cells and associated cytokines were positively correlated with AA disease duration.
Researchers also identified differences between AD subtypes. Patients with extrinsic AD were younger and demonstrated more severe eczema, higher total IgE levels, and greater dust mite allergy prevalence than those with intrinsic AD.
Researchers concluded that alopecia areata (AA) with comorbid atopic dermatitis (AD) represents a distinct clinical and immunological subtype of AA, characterised by more severe hair loss and increased type 2 immune activity, including elevated Th2 cells, ILC2s, and IL-13 production.
However, as the findings were based on a retrospective analysis, further prospective studies may be needed to validate this distinct clinical-immunological profile and clarify the relationship between AA and AD.
Reference:
Yan X et al. Investigation of Clinical and Immunological Features of Alopecia Areata with Comorbid Atopic Dermatitis. Allergy. 2026; DOI: 10.1111/all.70534.
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