Rejection of cartilage formed by transplanted allogeneic chondrocytes: evaluation with monoclonal antibodies

Abstract

Cellular infiltrates partcipating in rejection of cartilage formed by transplanted allogeneic rat epiphyseal chondrocytes were evaluated immunohistochemically using a panel of different monoclonal antibodies. One week after transplantation, the grafts were surround by numerous class II MHC + (OX6 +, OX17 +), CD4 + (W3/25 +), and W3/13 + cells as well as some ED1 + monocytes/macrophages. Only a few T (OX19 +) and B (HIS1r +) cells were present. The number of class II MHC + cells and ED1 + monocytes/macrophages did not change significantly in the course of rejection whereas the number of CD4 + and W3/13 + cells gradually decreased. On the other hand, there was a significant increase in the number of CD8 + (OX8 +) cells. CD8 + cells accumulated close to the transplants and some of them penetrated cartilage matrix suggesting that they might be involved in chondrocyte killing. After 3 months, cartilage was almost completely destroyed and the intensity of infiltration was markedly decreased. Fibrous connective tissue predominated, however, some class II + as well as few ED1 +, CD4 + and CD8 + cells were still present adjacent to the cartilage remnants. At the time of transplantation, chondrocytes were endowed with RT1.D class II antigen (OX17 +), but they did not react with OX6 mAb (monoclonal antibody) recognizing the RT1.B class II molecule. However, after 1 week, some chondrocytes reacted with OX6 mAb and the number of RT1.B positive chondrocytes increased in the course of cartilage rejection.