Abstract

Dogs have been treated after x-irradiation with doses of 400 r and 600 r by injection of either homologous or autologous bone marrow. The bone marrow was obtained by preirradiation biopsy and was reinjected either into the animal from which it was drawn (autologous) or into an alternate recipient (homologous). Injection of 2 x 109 autologous nucleated cells successfully protected all dogs given either 400 r or 600 r. Dogs given 1 x 109 autologous nucleated cells after 600 r failed to survive. No protection was provided by injection of 2 x 109 homologous nucleated cells after 400 r nor by injection of 2 x 109 or 5 x 109 homologous nucleated cells after 600 r. It is proposed that a differential species sensitivity to foreign cell implants accounts for the failure of homologous marrow infusions in dogs in contradistinction to the protection provided by homologous or heterologous marrow implants in rats and mice, and by homologous implants in monkeys.

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