Accelerated Rejection of Skin Homografts by Vitamin a Acid

SUMMARY The effect of vitamin A acid on the survival of CBA/H skin grafts in C3H mice and vice versa was investigated. If the recipient C3H mice were treated weekly with 100 and 200 mg/kg of vitamin A acid, CBA/H homografts were rejected more expeditiously, namely, after approximately 20 days instead of 40. With C3H homografts in CBA/H mice, a less marked curtailment was seen. Iso- and autografts were not affected by equal dosages of vitamin A acid. However, at 400 mg/kg/week, it caused their breakdown. It is therefore unlikely that a reinforcement of the hosts' immune response is responsible for the accelerated homograft rejection, but as it occurs at dosages which do not interfere with the healing process of grafts, vitamin A acid is thought to increase the susceptibility of skin transplants to the immunological rejection.