The immunosuppressive effect of concanavalin A in monkeys

These studies were performed to evaluate the immunosuppressive effect of concanavalin A (ConA) in monkeys. Bonnet monkeys (Macaca radiata) weighing between 2.5-3.5 kg were used. Following the exchange of full thickness skin allografts in randomly selected animals, gross and histopathological studies of the rejection reaction were performed. Gross observations showed the allograft reaction in control animals to be a well defined phenomenon occurring at 9.0 +/- 0.7 days. In contrast the rejection process in animals that received i.v. ConA was a poorly defined prolonged process occurring at 14.8 +/- 3.9 days (single 75-mg dose of ConA), and 19.0 +/- 2.2 days (75 mg 1 day before and 25 mg 3 days after grafting). In monkeys that received the double dose schedule of ConA, histopathological studies showed distinct retardation of the rejection reaction with reduced lymphocytic infiltration of the graft-host junction. Control grafts showed almost complete rejection in 7-9 days while allografts on ConA-treated animals showed corresponding degrees of destruction only by the 15th day. These studies indicate that ConA does have an immunosuppressive effect in vivo in monkeys. The local and systemic toxic effects of ConA encountered in these animals have been reported and its haematological effects in vivo briefly described.