Objective To observe the damage to Langerhans cells induced by UVB irradiation,and to evaluate photoprotective effect of these cells from UVB irradiation by epigallocatechin-3-gallate (EGCG).Methods Biopsy specimens were obtained from normal adult foreskin,and epidermal cells were isolated.Density gradient centrifugation and magnetic cell sorting were used simultaneously to purify Langerhans cells from the cell suspension.These cells were then divided into three groups,control (no ir- radiation or EGCG trea...