Cynomolgus monkeys have served as renal transplant donors and recipients. It is known that Class II MH6 antigen is pivotal to antigen recognition and the immune response. The use of antibodies to Class II has been limited in humans and other primates because of Class II expression of endothelium and other tissues. We are in the process of trying a new antibody gLE1 which shows to have minimum toxicity in cynomolgus monkeys. If this continues to hold true, it will permit studies of its role in transplant immunosuppression. If the gLE1 treatment is successful in preventing organ rejection, further combination studies will be planned with gLE1 and other immunosuppressive therapies.