Illustration of a skin contact allergy. at first contact. the reaction phase and second contact. the allergic reaction manifests itself. During the first contact with allergens. the dendritic cells capture the allergens then migrate to the lymph nodes (a phase simplified by the yellow arrow). Immune response by the T or B cells (blue or purple cells) with the production of IgE antibodies which recognise the allergen. The IgE latches onto the mast cells (pink cell in the epidermis). After the reaction phase. any contact with the allergen will cause an allergic reaction. The allergen comes into contact with the mast cells which recognise it. It releases inflammatory substances (green). such as histamine. which is responsible for oedemas and itchy skin.