Characterization of CD4+ T cell subsets in allergy

Allergen specific TH2 cells are a key component of allergic disease, but their characterization has been hindered by technical limitations and lack of epitope data. Knowledge about the factors that drive the differentiation of naïve T cells into allergy-promoting TH2 cells and the influence of allergen specific immunotherapy on the phenotype and function of allergen-specific T cells have also been limited. Recent advances indicate that innate and adaptive immune factors drive the development of diverse subsets of allergen-specific T cells. While allergen-specific T cells are present even in non-allergic subjects, highly differentiated TH2 cells are present only in allergic subjects and their disappearance correlates with successful immunotherapy. Therefore, elimination of pathogenic TH2 cells is an essential step in tolerance induction.

► New assays and epitope data have advanced the study of allergen specific T cells.
► Allergen specific T cells are present in allergic and non-allergic subjects.
► Allergen specific T cells differentiate into diverse phenotypes in allergic subjects.
► TH2 cells are selectively deleted during ASIT because of increased apoptosis.
► Depletion of allergen-specific TH2 cells is requisite for the induction of tolerance.