Studies of experimentally induced immune phenomena, as they occur in the cornea, have revealed that this avascular tissue is apparently able to support cellular-mediated as well as antibody-mediated hypersensitivity reactions.1 The authors have previously shown that both types of immune response which follow sensitization of the cornea to a soluble protein antigen (bovine serum albumin [BSA] ) can be inhibited if the antimetabolite 6-mercaptopurine (6-MP) is administered concomitantly with the antigen.2 The drug maintains the cornea in a transparent state and suppresses antibody production as well as the infiltration of the limbus by specific, immunologically competent cells.
In the present study, the initiation of 6-MP therapy was varied with respect to the time of introduction of a foreign protein into the cornea. In this manner, the immunosuppressive efficacy of (1) Pretreatment, (2) short term administration of the drug, and (3) delayed initiation of therapy upon corneal hypersensitivity was investigated.
LEIBOWITZ HM, ELLIOTT JH. Further Studies on the Suppression of Corneal Hypersensitivity by Antimetabolites. Arch Ophthalmol. 1965;74(6):835-840. doi:10.1001/archopht.1965.00970040837020