Both fresh and frozen allogeneic bone elicit both acellular and humoral
immune response. This response includes the development of enhancing
factors which block detectable immunity and probably protect the graft from
rejection. There seems to be no evidence of an alteration in immunogenicity
by freezing of the graft. The importance of these observations lies in the
potential technique of employing fresh viable allografts; prior freezing
and tissue matching for HL-A transplantation antigens should not be
necessary.