In vitro reactivity of alveolar macrophages and red blood cells with asbestos fibres treated with oxalic acid, sulfur dioxide and benzo-3,4-pyrene.

The effects of 3 UICC asbestos fibres (A chrysotile, crocidolite, amosite) were observed in vitro on red blood cells (RBC) and alveolar macrophages (AM). THe reactivity of the fibres after leaching with 0.1 N oxalic acid or adsorption of SO2 or benzo-3,4-pyrene (BP) was studied. The haemolytic activity of crocidolite and amosite was very low. A cytotoxic effect on AM occurred when the fibres were present in high concentration (100 microgram/ml), this was characterized by a release of both cytoplasmic (LDH) and lysosomal (beta-galactosidase) enzymes. The leached fibres were more haemolytic than the unleached ones, and more beta-galactosidase (beta-Gal) than lactic dehydrogenase (LDH) was released from the AM. In contrast to the amphiboles, chrysotile fibres were highly haemolytic and induced a selective release of beta-Gal from AM. Leached fibres were less haemolytic and were cytotoxic for AM (both enzymes were released). Their in vitro reactivity was similar to that observed with quartz. The results showed that SO2 changed the reactivity very little. BP sorption on acid-leached chrysotile decreased the LDH release from AM. The difference in the in vitro reactivity related to the chemical state of asbestos fibres might explain the difference in their in vivo reactivity (latency, degree of fibrosis). This point is discussed.