this suggests that there are two phases in the response of the epidermal ia antigens in contact sensitivity reactions , i.e . an early phase in which enlarged langerhans cells are the only ia-positive cells in the epidermis , and a late phase in which keratinocytes take over as the major ia-positive cells , while langerhans cells resume their original size .
C0014520
epidermis
C0023005
langerhans cells