Atopic dermatitis and its treatments. Cut of skin with, in bottom, the different stages of evolution of the dermatitis: from left to right, erythematous stage in the phase of triggering, by the allergen, vesiculous stage, oozing stage, then crustose stage. A dilated blood vessel releases mast cells and LTCD4 Th2 lymphocytes releasing cytokines. The IgE produced by the lymphocytes will bind to the dendritic cells of Langerhans. In cartridge, the sensitization phase to the allergen on normal skin. A Langerhans cell presents the allergen in the lymph node, triggering the production of IgE secreting CD4 Th2 LT cells.