Cartilage produced after transplantation of syngeneic chondrocytes is rejected in rats presensitized with allogeneic chondrocytes.

Cartilage produced in 2-week-old intramuscular transplants of syngeneic chondrocytes in rats did not display any signs of rejection. Cartilage produced by similar transplants in animals presensitized with intramuscular transplants of allogeneic chondrocytes was surrounded by infiltrations composed mainly of lymphocytes and was partially resorbed. Spleen mononuclear cells (SMC) from recipients of syngeneic transplants alone were not stimulated in mixed splenocyte-chondrocyte cultures by syngeneic or allogeneic chondrocytes. SMC from recipients of allogeneic and subsequent syngeneic transplants were strongly stimulated by both syngeneic and allogeneic chondrocytes, although stimulation by the latter was significantly more pronounced. Sera from naive rats usually contained cytotoxic antichondrocyte antibodies but their level varied considerably in various individuals. In rats chosen as transplant recipients on the basis of low antichondrocyte cytotoxicity of their sera, this toxicity was markedly raised after sensitization with allo- and syngeneic chondrocytes. Absorption with thymocytes or fibroblasts decreased but did not abrogate cytotoxicity. These observations support previous reports suggesting expression of tissue-specific antigen(s) by chondrocytes.