Is a corneal transplantation immunologically privileged from graft rejection?

It has been known that a corneal graft can induce an allograft rejection reaction even in such an "immunologically privileged site". Reliable microsurgical techniques, together with the availability of inbred or congenic strains and a rapidly developing knowledge of its major histocompatibility complex (MHC) and immune system in general, have made the rat a prime species in which to study the immunological events after corneal grafting. This review describes recent progress in understanding the immunological mechanisms behind clinical corneal graft rejection. The topics discussed include the rat major histocompatibility complex (MHC) (RT1) antigens and their distribution in the cornea and the role of antigen-presenting cells (ARCs) in corneal graft rejection.