Influence of macrophages on microdistribution of inhaled UO₂aerosol in rat lung

Abstract

Following the inhalation of an aerosol of UO2 (mass median aerodynamic diameter = 3 microns and geometric standard deviation = 1.6) the lungs of male albino rats were populated by foci containing UO2 particles. A method of neutron-induced autoradiography on Lexan plastic was used to reveal these foci in thin sections cut from the lung. For masses of UO2 in the lung that differed by more than a factor of 10 (39 to 450 micrograms) the number of foci per g of lung increased, but not in proportion to the mass of UO2 deposited. This limited increase in the number of foci was considered to result from physiological limitations on the number of alveolar macrophages available for engulfing the UO2 particles.

Uranium carcinogenicity in humans might depend on the physical and chemical nature of uranium and its isotopic composition: results from pilot epidemiological study of French nuclear workers

“…In the case of small particles (about 5 lm, the most common in the nuclear industry), the lung-associated lymph system is the dominant route for physical translocation from the pulmonary region [51,52]. Pulmonary alveolar macrophages play a crucial role in this translocation because of their ability to phagocytize UO 2 particles despite the metal's high toxicity relative to cell membranes [19,53,54]. Insoluble UO 2 and PuO 2 particles remain within the lysosomes of macrophages and may damage the lysosomal membranes.…”

Biokinetics of nuclear fuel compounds and biological effects of nonuniform radiation.

“…Some particles may directly enter the alveolar interstitium by pinocytosis (84). There are also indications that the particles in the lungs are redistributed or aggregated due to macrophage migration and grouping (85), which may change the radiation dose or injury pattern. Water-insoluble radionuclides are absorbed in accordance with their dissolution rate, partition coefficient, and residence time in the respiratory tract (62).…”