Birbeck granules on blood BDCA-1⁺ DCs treated with TSLP and TGF-β. After 3 days of culture with TSLP and TGF-β, blood BDCA-1⁺-derived LCs were sorted according to the expression of CD1a and CD207. Electron microscopy pictures show the presence of LC characteristic Birbeck granules in the cytoplasm (arrows). The Birbeck granules shown in the lower pictures correspond to different independent cells. The experiment was performed for 6 independent blood donors and found Birbeck granules in the CD1a⁺CD207⁺ cell population for all tested donors.