The site dependence of the articular cartilage transplant reaction.

Allografts of immature joint cartilage from the knees of lambs were transferred heterotopically into an intramuscular site in animals which had been presensitised by two sets of skin grafts from the same donors. All of these grafts were found to be largely destroyed by the immune response as early as four weeks after transfer. Similar grafts transferred orthotopically into the knees of the recipients, on the other hand, were found to be thriving even after twelve weeks and evoked a minimal response. Heterotopic autografts also provoked a mild though non-specific inflammatory reaction which the orthotopic grafts did not. It is concluded that cartilage matrix is capable of protecting grafts to a remarkable degree even from a severe immunological assault but only when the nutrition is adequate. It is suggested that the conflicting results of similar previous experiments may be explained by variations in the nutritional state of the graft which may be affected by the technique of transplantation used.