C57BL/6 islet allograft survival in diabetic NOD/Lt recipients of C57BL/6 bone marrow.

Both chimeric and nonchimeric NOD/Lt mice from among those described in Table 2 were selected at random and transplanted with a C57BL/6 islet graft 5 to 7 weeks after bone marrow transplantation as described in “Materials and Methods.” All mice were diabetic at the time of both bone marrow and islet transplantation; their diabetes was treated with sustained-release insulin pellets until islet transplantation, at which time the pellets were removed. For purposes of analysis, mice were divided into 3 groups. Mice in group 1 had received 600 to 900 rad of conditioning radiation plus anti-CD154 mAb and were chimeric. MST of islet grafts in this group was more than 120 days. Mice in group 2 had received 600 to 800 rad of conditioning radiation and anti-CD154 mAb and were nonchimeric. Mice in group 3 had received 600 rad of radiation but no anti-CD154 mAb and were nonchimeric. MST of grafts in groups 2 and 3 was 3 days. Graft survival in group 1 was significantly longer than in the other groups (P<.0001). Graft survival in groups 2 and 3 was statistically similar. Censored data—mice that died or were nephrectomized at the end of the experiment—are indicted by vertical lines.