The antigenicity of deep-frozen and freeze-dried cortical and
corticocancellous bone allografts placed orthotopically in rabbits was
studied using a sensitive microcytotoxicity assay. Target cells were
phytohemagglutinin-P-stimulated, 51chromium-labeled peripheral blood
lymphocytes from the bone donors (Dutch belted rabbits), and sera or
peripheral blood lymphocytes from the graft recipients (New Zealand white
rabbits) were used as effectors of cytotoxicity. Fresh allografts and
deep-frozen corticocancellous bone evoked detectable humoral and
cell-mediated immunity,, whereas freeze-dried cortical bone allografts
failed to sensitize the recipients and were the least antigenic of the
allografts examined.