The role of resident accessory cells in corneal allograft rejection in the rabbit.

Corneal grafts are more likely to be rejected when placed in a vascularized rather than in a normal host cornea. Using immunohistochemical techniques, normal rabbit cornea was found to contain measurable numbers of cells of hemopoietic origin, probably of either macrophage or dendritic lineage. After the deliberate induction of corneal inflammation and neovascularization, the number of these accessory cells was found to increase significantly. There was also a marked increase in the number of T cells present. Enzyme staining indicated a degree of heterogeneity in the infiltrate. The process of rejection of rabbit corneal grafts was found to occur earlier when additional infiltrating cells were present in either donor button or graft bed, and earlier still when the load of infiltrating cells was increased in both donor and recipient. We hypothesize that resident accessory cells of recipient origin may be implicated in graft rejection in vascularized, inflamed corneas.