The interaction between chrysotile and three lysosomal enzymes (acid phosphatase, acid RNase and acid protease) in isolated lysosomal enzyme-rich preparations (LEP), from sheep alveolar macrophages maintained in the presence and absence of serum components or pulmonary surfactant at pH 5.0 and pH 7.0 for up to 22 days, is investigated. It is concluded that chrysotile does not inhibit or enhance lysosomal enzyme activity at either pH but may preferentially absorb specific enzymes and that the binding reaction between any given enzyme and mineral can be dependent on the presence of other organic compounds. The release of three hydrolytic enzymes (beta-galactosidase, acid RNase and protease) from cultured rabbit alveolar macrophages, in the presence of different concentrations of bovine serum (5-20%) and in the presence and absence of chrysotile for 72 hr, was also studied. Chrysotile enhances early differential release of each hydrolytic enzyme, but after 72 hr both control and chrysotile-treated cultures (maintained in 10-20% serum) have very similar intra- and extracellular levels of hydrolytic activity. The apparent differential release of lysosomal enzymes by untreated macrophages, which is dependent on serum concentration and time in vitro, is discussed.