Detection of metallothionein in bronchoalveolar cells and lavage fluid following repeated cadmium inhalation.

Metallothionein (MT) levels were measured by radioimmunoassay in bronchoalveolar cells and fluids derived from rat lungs following 0, 8, 12, 18, or 24 exposures to Cd acetate aerosols. Alveolar cell metallothionein levels increased from a base line value of 0.35 micrograms MT/mg protein in control rats to a value of 21.73 micrograms MT/mg protein in rats exposed 24 times to Cd aerosols. Cell-free lavage fluid levels of metallothionein also increased in response to frequency of Cd exposure but were 5 to 10-fold lower than in the free alveolar cells. Gel chromatographic analysis of free alveolar cells from Cd-exposed animals revealed the presence of a 11,600-Da Cd-binding protein with an absorption maximum of 254 nm. Metallothionein analyses of purified populations of alveolar macrophages and polymorphonuclear leukocytes from exposed animals demonstrated that macrophages but not polymorphonuclear leukocytes contained metallothionein.