Novikova MN, Nemenova NM, Malanina VN: Hematopoiesis in long-term survival following supralethal irradiation and bone marrow transplantation in dogs.

B ONE MARROW TRANSPLANTATION may effectively protect dogs exposed to whole-body ionizing radiations of 2 to 3 LD95. Hematopoiesis was investigated at remote periods after the exposure, when the hematopoietic stem cells had been proliferating in the lethally irradiated organism for a long time. Ferrebee and his associates’6 succeeded in attaining long-term survival of supralethally irradiated dogs given autografts of bone marrow or allografts and methotrexate. However, no details concerning bone marrow hematopoiesis in these animals were given. The only information was that 6 months to 4 years subsequent to exposure, the leukocyte, reticulocyte, and thrombocyte counts and the hemoglobin level in the peripheral blood were within normal ranges. For a number of years this laboratory has been investigating the effect of hematopoietic cell transplantation in radiation lesions. It was shown in earlier works7 3 that usually bone marrow allografts have no positive effect on lethally irradiated dogs owing to the rapid transformation of the introduced hematopoietic cells into lymphocytes immunologically active against the recipient, a circumstance conducive to the cessation of normal hematopoiesis. The dogs expire within two weeks following exposure. In a number of cases713 we succeeded in preventing or inhibiting the lymphoid transformation of the transplanted allogeneic cells by resorting to transplantation of mixed bone marrow derived from several donors, delayed transplantation of the bone marrow, transplantation of filtered (through a plug of cotton) bone marrow, predominantly containing lymphoid cells and erythronormoblasts, etc. Several of the animals treated thus survived. On the other hand, a good protective effect was obtained by transplantation of bone marrow autografts. Thus we were in a position to investigate hematopoiesis at remote periods after exposure to two lethal doses of ionizing radiation in dogs protected by allogeneic or autologous hematopoietic cells.