Studies of the behaviour of allogeneic cancellous bone grafts in inbred rats

The degree of new bone formation in isografts and allografts has been assessed by a radiotracer technique. Allografts used have been either H-1-identical or H-1-disparate with the recipient. It was found that new bone formation is curtailed within the first 3 weeks after grafting. This curtailment was significantly greater in those donor-recipient combinations which were H-1-identical but disparate for many weak locus antigens than those in which H-1 disparity existed with only a few minor locus differences. There was no late phase (i.e., host-derived) osteogenesis in the combination with H-1 identity, but multiple minor antigen disparities. In isografts and H-1-disparate grafts significant late phase osteogenesis was found in about 30% of recipients. Resorption of the graft was found to be significantly impaired in both H-1-identical and disparate grafts in comparison with isografts. There was a significant negative correlation between weight of the graft and degree of osteogenesis in isografts during the first 2 weeks after grafting, and also during the later phase (6-8 weeks). A similar negative correlation was found during the late phase in H-1-disparate grafts with few minor antigen disparities, but no correlation was found at any time in H-1-identical grafts with multiple minor antigen disparities.