Inhibition of Immune Corneal Graft Rejection by Azathioprine (Imuran)

Penetrating corneal homografts in vascularized rabbit corneas are regularly rejected if skin from the corneal donor is grafted to the corneal recipient.¹⁻⁴The 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;⁵⁻⁶in its absence, even lamellar heterografts can remain clear indefinitely.⁶⁻⁷One 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,⁶but 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