Atopic Multimorbidity in Adults With a Focus on Sensitization Patterns and T Cell Activation

Atopic diseases-including atopic dermatitis (AD), asthma (AA), and allergic rhinitis (AR)-are driven by Th2 inflammation and often occur together (atopic multimorbidity), along with non-atopic comorbidities. Chronic spontaneous urticaria (CSU) is an autoimmune mast cell-driven disease, but its relationship to classic atopic diseases remains unclear. This study investigated the association of CSU with classical atopic diseases as well as sensitization patterns and T cell activation in atopic multimorbidity.

We conducted a prospective, single-center study involving 123 participants who completed structured questionnaires regarding physician-diagnosed AD, AA, AR, and/or CSU, as well as non-atopic comorbidities and a history of type I sensitizations. AD patients (n = 22, with or without AR/AA, but not CSU) and healthy controls (n = 20) underwent additional immunophenotyping. Peripheral blood T cell subsets and T cell activation status were measured by flow cytometry and compared across groups.

Individuals with atopic multimorbidity exhibited more frequent type I sensitizations, sleep disorders, and elevated serum IgE levels. CSU differed from classical atopic diseases regarding age of onset and duration and was therefore excluded from immunophenotyping. T cell subsets and activation in AD did not differ by presence of atopic multimorbidity but correlated with disease activity scores.

Our findings highlight the burden associated with atopic multimorbidity, demonstrated by increased serum IgE and sensitization rates in individuals with multiple atopic diseases. Importantly, T cell activation appeared to be more closely related to AD disease activity rather than the presence of classic atopic comorbidities.