Basophils are not the key antigen-presenting cells in allergic patients.

Background Recent data obtained in mouse models have initiated a controversy whether basophils are the key antigen-presenting cells (APCs) in allergy. Here, we investigate whether basophils are of importance for the presentation of allergen and the induction of T cell proliferation in allergic patients. Methods T cells, basophils, and APCs depleted of basophils were purified from allergic patients. Co-culture systems based on purified major allergens were established to study allergen-specific T cell responses using proliferation assays. Results Only co-cultures of T cells with APCs depleted of basophils but not with basophils proliferated in response to allergen. Even addition of IL-3 to T cell–basophil co-cultures failed to induce allergen-specific T cell proliferation. Conclusions Our data demonstrate by classical in vitro proliferation assays that basophils are not key antigen-presenting cells that promote T cell proliferation in secondary immune responses to allergen in allergic patients.