Prolonged survival of rat leg allografts due to immunological enhancement

Attempts were made to induce a prolonged survival of leg allografts in rats by means of immunological enhancement. AS rats injected with AS anti-August antiserum accepted (AS X August)F1 kidney allografts for longer than 50 days, but rejected F1 leg allografts within 12-16 days. However, AS rats bearing established, enhanced (AS X August)F1 kidneys accepted F1 leg allografts for periods of 21-207 days. The possibility is discussed that composite tissue allografts can manifest prolonged survival provided that their recipients have passed through the "induction phase" of enhancement and reached the "steady-state" or maintenance phase.