Differential survivals of F1 hybrid allografts in parental recipients.

Differential survival times of various organ allografts in the rat across the same histocompatiblity barrier were studied by transplanting the kidney, heart, intestine, pancreas, and skin from (BN X Le)F1 hybrid donors to Lewis recipients. Some (one-third) of the kidney grafted rats survived for a prolonged period of time (32-72 days, plus one rat surviving over 9 months), whereas all other organs and skin were promptly rejected between 7 and 21 days. Possible factors responsible for the prolonged kidney survival are discussed; the reason for this was not clear but was not related to the period of operative ischemia or postoperative blood-urea-nitrogen, nor were animals tolerant to donor antigen as evidenced by the popliteal lymph node weight assay and signs of mild rejection on histology of grafted kidneys. A hypothesis of autoenhancing mechanism is presented.