Penetrating corneal homografts in vascularized rabbit corneas are regularly rejected if skin from the corneal donor is grafted to the corneal recipient.1-4 The delayed graft reaction and the similarity of the clinical picture in experimental and in human grafts point to a common immunological type of reaction.
Corneal vascularization is required for the experimental immune rejection of corneal homografts;5-6 in its absence, even lamellar heterografts can remain clear indefinitely.6-7 One of the problems found in clinical cases of corneal homotransplantation is how to prevent the late corneal graft rejection (or graft sickness) when the transplant has been done in a vascularized host. To a certain extent, corticosteroids can prevent or diminish the reaction,6 but in most cases, they fail to prevent opacification of the transplant.
The successful use of antimetabolites, especially 6-mercaptopurine (6-MP) and its derivative azathioprine, in preventing the rejection of highly vascularized organs such
POLACK FM. Inhibition of Immune Corneal Graft Rejection by Azathioprine (Imuran). Arch Ophthalmol. 1965;74(5):683-689. doi:10.1001/archopht.1965.00970040685018