An experimental study on bone allograft in rats : using immunohistochemistry and radioimmunoassay

The purpose of this study was to investigate the rejection mechanism of the allografted bone tissue through the change of the location and intensity of the major histocompatibility complex (MHC) antigen expression on the osteocyte and the changes in the alloantibody levels using immunohistochemistry and tadioimmunoassay. The following conclusions were obtained through this study. (1) Some osteocytes wxpress MHC Class I antigen in the normal rat bone tissue. The expression of MHC Class I antigen on osteocytes showed diversity. However, the expression of MHC Class I antigens on osteocytes ofallografted bone tissue uncreased with time after bone allograft transplantation. (2) Three weeks after allograft transplantation, a severe decrease of osteocytes in allografted bone tissue was observed. Almost all the remaining osteocytes expressed MHC Class I antigen strongly in the allografted bone tissue in DA to F334 strain combination. (3) F334 weeks recipients of DA rat bone grafts developed high titers of allonatibody anti-Class I. This titer increased from 2 weeks after transplantation and it kept still high levels even 14 weeks after transplantation. (4) MHC Class I antigens might play an important role in bone allograft rejection as has been observed in other transplanted organs in the rat.