Effects of well-defined fibres on red blood cells and alveolar macrophages.

The fibres used in this experiment were UICC asbestos fibres (chrysotile, amosite, crocidolite, either untreated or leached with oxalic acid), nemalite and glass fibres. Chrysotile was also treated with sulfur dioxide. Size distribution measurements by electron microscopic analysis, chemical analysis and measurement of specific surface area were performed. Haemolytic activity was studied in human red blood cells by kinetic analysis of the percentage of haemoglobin released; this generated information on the shape of the curve, the initial velocity of the haemolysis and the maximal haemolysis. The effect on rabbit alveolar macrophages was determined in vitro by the measurement of lactic dehydrogenase and beta-galactosidase released from alveolar macrophages cultured with the fibres. Amphiboles and chrysotile had opposite reactivities on red blood cells. Leaching did not change the shape of the curve with chrysotile whereas it modified that with amphiboles. The initial velocity decreased with leached chrysotile and increased with leached crocidolite or amosite. Maximal haemolysis was linearly dependent on the fibre concentration with amosite and crocidolite, but not with chrysotile or nemalite. The adsorption of sulfur dioxide onto chrysotile did not highly modify its haemolytic activity. In alveolar macrophages, chrysotile and leached amphiboles selectively released beta-galactosidase; and leached chrysotile and nemalite released both enzymes studied.