Radiation-Induced Hematologic and Nonspecific Immunologic Effects in the Canine

摘要

A canine model was used to assess the effects of irradiation on bone marrow progenitor cellularity, peripheral blood leukocyte and platelet cellularity,and phagocytosis-induced granulocyte oxidation burst activity. Sexually mature beagles were bilaterally exposed 2 Gy of cobalt-60 radiation, and at various times postirradiation bone marrow and peripheral blood samples removed. Bone marrow granulocyte-macrophage progenitor cell (GM-CFC) numbers were reduced to approx. 10% of normal by 24 hours postexposure, and full recovery to normal GM-CFC levels was not seen until day 49 postirradiation. Peripheral blood leukocyte and platelet values were also dramatically reduced postirradiation; by day 49 postexposure, these values had recovered to only approx. 90% of normal. The ability of percoll-isolated peripheral blood granulocytes to mount an oxidative burst in response to opsonized zymosan also decreased following irradiation. By contrast, the ability of nonisolated peripheral blood granulocytes (i.e., granulocytes in whole blood) to mount an oxidative burst in response to opsonized zymosan increased following irradiation. When sera obtained from dogs at various times postirradiation were assayed for ability to enhance the oxidative burst capacity of normal percoll-isolated peripheral blood granulocytes, stimulatory activity was detected as early as a day 2 postirradiation and persisted through day 29 postexposure. These results suggest that, although peripheral blood granulocyte numbers are decreased following radiation injury due to stem cell damage, humoral factors may enhance the function of the available granulocytes in irradiated animals.