ABSTRACT
At the present time, the toxic side effects of recipient immunosuppression cannot
be justified for human non-vital organ transplantation. Total body irradiation has
proven effective in ablating various bone-marrow-derived and endothelial immunocompetent
cellular populations, which are responsible for immune rejection against donor tissues.
Irradiation at a dose of 10 Gy was given to donor rats six days prior to heterotopic
transplantation of vascularized bone allografts to host animals. Another group of
recipient rats also received a short-term (sixth to fourteenth day after grafting),
low dose of cyclosporine.
Total body irradiation was able merely to delay rejection of grafts across a strong
histocompatibility barrier for one to two weeks, when compared to nonirradiated allografts.
The combination of donor irradiation plus cyclosporine did not delay the immune response,
and the rejection score was similar to that observed for control allografts. Consequently,
allograft viability was quickly impaired, leading to irreversible bone damage.
This study suggests that 10 Gy of donor total body irradiation delivered six days
prior to grafting cannot circumvent the immune rejection in a vascularized allograft
of bone across a strong histocompatibility barrier.
