The unique paucity of Ia+ Langerhans cells (LCs) in the central cornea contributes to the immunological privilege of corneal allografts. A variety of stimuli can induce the centripetal migration of peripheral LCs. At least one of these stimuli (i.e. latex bead instillation) induces interleukin-1 (IL-1) secretion by corneal cells which acts as a potent chemoattractant for LCs. Within 30 minutes of intracorneal injection of IL-1, centripetal migration of LCs can be detected. The presence of donor-derived LCs in corneal allografts doubles the incidence of rejection of fully allogeneic corneal allografts as well as MHC matched, multiple minor H mismatched corneal allografts. Although the presence of donor-specific LCs greatly jeopardises corneal allograft survival, migration of host-derived LCs into corneal allografts does not appear to increase the risk of rejection.