Alveolar macrophage kinetics after inhalation of 239PuO2 by CBA/Ca mice: changes in synthesis of DNA.

For workers in the nuclear industry, the primary route for the entry of radioactive materials into the body is by inhalation, and the rate of clearance of particles from the pulmonary region of the lung is an important factor in determining radiation dose. It is the function of alveolar macrophages (AM) to maintain the sterility of the lung and to remove insoluble particles from the respiratory surfaces and airways. The AM population is not static, and under normal conditions the loss of macrophages from the alveoli via the conducting airways is balanced by renewal. Studies of the effects of external irradiation on the kinetics of AM are numerous, but to date little is known about the effects of inhaled radioactive particles. In this investigation the effects of inhaled 239PuO2 (plutonium dioxide) particles on the synthesis of DNA by AM were studied at times up to 77 days after exposure. We also measured the number of cells recovered by bronchoalveolar lavage and the incidence of AM with nuclear aberrations. The latter provides a sensitive indicator of the effects of radiation. One of the earliest effects observed after exposure to 239PuO2 is a reduction in the number of AM recovered by lavage. This reduction is associated with a 3-fold reduction in the proportion of AM undergoing DNA synthesis at early times after exposure. The overall mean pulse labeling index of AM recovered from sham-exposed mice is 1.68%, and no trend is observed with time.(ABSTRACT TRUNCATED AT 250 WORDS)