Experiments were described using centrifugal elutriation to study chlorphentermine (461789) induced phospholipidosis in alveolar macrophages from male Long-Evans-hooded-rats treated 5 days a week for 4 weeks with chlorphentermine, 30mg/kg intraperitoneally. Alveolar macrophages from lung lavage were separated into four subpopulations, based on size. Each subgroup was examined for certain biochemical properties. Cells from treated rats demonstrated an 18 fold increase in phospholipid content over controls. The lipidotic cells contained about three times as much protein as control macrophages, resulting in a six fold enrichment in the phospholipid to protein ratio within the cells. Increased levels of acid-phosphatase and beta-N-acetylglucosaminidase were also seen. Significant increases in phospholipid and protein content, lactate-dehydrogenase activity, and lysosomal enzyme activities were seen with increasing cell size. The increases were linear for phospholipid, protein, and lysosomal enzymes with respect to the increase in cell volume. Of the five biochemical properties examined, phospholipid content increased most closely with cell volume increases. Acid-phosphatase and beta-N-acetylglucosaminidase activities increased equally as the cells enlarged. Smaller increases in protein, phospholipid, and enzyme activities were noted in control cells as they became larger also. The authors conclude that with this method of separating cells into more homogeneous groupings, it will now be possible to learn more specifically what effects drug induced phospholipidosis have on alveolar macrophage function.