This can identify foods causing non-IgE-mediated reactions (use a normal skin prick test for IgE allergies). APT is thought to provide evidence for a T-cell-mediated reaction. APT is performed by placing the food in its native state in contact with the skin under an aluminum Finn Chamber for 48 h on the patient's back. The chamber is removed and the reaction is examined for induration and papules 24 h later.
