Allergen-specific T-helper 2 cell (Th2 cell)

Allergen-specific T-helper 2 (Th2) cells are a specialized subset of CD4+ T lymphocytes that orchestrate the adaptive immune response to allergens. Upon activation by antigen-presenting cells, these cells secrete a signature profile of cytokines, including IL-4, IL-5, and IL-13, which drive the pathophysiology of allergic diseases such as asthma, atopic dermatitis, and allergic rhinitis. IL-4 and IL-13 are critical for B-cell class-switching to IgE, while IL-5 promotes the recruitment and survival of eosinophils. A specific pathogenic subset, termed Th2A cells, has been identified by the co-expression of markers like CRTH2 and CD161 and is found almost exclusively in allergic individuals. Therapeutic targeting of these cells involves both symptomatic management and disease-modifying strategies. Allergen-specific immunotherapy (AIT) works by inducing a shift from a Th2-dominant response to a regulatory T cell (Treg) response, promoting the production of suppressive cytokines like IL-10 and protective IgG4 antibodies. Biologic therapies, such as dupilumab and mepolizumab, interfere with the Th2 pathway by blocking cytokine receptors or the cytokines themselves. Emerging small molecules like soquelitinib target intracellular signaling pathways, such as the ITK kinase, to inhibit Th2 differentiation and effector function.

Other names

Th2 cellsType 2 helper T cellsAllergen-specific CD4+ T cellsTh2A cellsPathogenic Th2 cells

Inhibition of type 2 cytokine signaling (IL-4, IL-5, IL-13), induction of immune tolerance via T-regulatory cell differentiation, and blockade of T-cell receptor signaling kinases like ITK.