THE EFFECT OF IONIZING RADIATION ON PHAGOCYTOSIS AND THE BACTERICIDAL POWER OF THE BLOOD

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Abstract
Rats irradiated with 600 r (total body) showed increased indices of both opsonophagic and surface phagocytosis 2, 12, and 24 hours after irradiation. The indices decreased 72 hours after exposure and returned to normal by the 4th-5th post irradiation day. Bactericidal power of the blood of irradiated animals was depressed when measured 3 and 6 days after exposure to X-rays. Decomplemented serum from irradiated animals was more bactericidal against Micrococcus aureus than decomplemented serum from control rats. This bactericidal substance was destroyed at 78[degree]C; it did not require any complement or specific antibodies for action. Extracts of leukocytes from animals 3 days after irradiation demonstrated no bactericidal activity against M. aureus. while extracts from control animals or rats 1 day after irradiation were actively bactericidal. Extracts from leukocytes of non-irradiated animals were thermolabile, non-dialyzable, had a pH optimum of 7.5, and could be precipitated by NH4SO4 and fractionated by calcium phosphate. The observed increase in susceptibility of irradiated rats to infection with M. aureus was correlated not only with granulopenia but also with alteration of the above indicated functions of the granulocytes of irradiated animals.