Human bone allografts can induce T cells with high affinity for donor antigens

We analysed the cellular immune response in ten transplantations of differe nt massive bone allografts, of which five had a poor clinical outcome. Cyto toxic T lymphocytes (CTL) and T helper lymphocytes (TH) against mismatched donor antigens were found in all patients. More importantly, CTL with a hig h affinity for donor antigens were found in five cases. High-affinity CTL n eed no CD8 molecule to stabilise the antigen binding and are strongly assoc iated with rejection of heart and corneal transplants. Even after removal o f most of the bone-marrow cells, we found high-affinity CTL and high TH fre quencies. This T-cell response could be detected over a period of years. We conclude that frozen bone allografts can induce high-affinity donor-spec ific CTL. The present assay allows qualification and quantification of the levels of CTL and TH in the blood. This approach may be helpful in studying the effect of the immune response on the outcome of the graft.