. (1971). Brit. J. industr. Med., 28, 179-185. Effects of chrysotile and acid-treated chrysotile on macrophage cultures. The addition of chrysotile asbestos to monolayer cultures of peritoneal and alveolar macrophages produces an increase in membrane permeability, as measured by eosin uptake and lactic dehydrogenase activity of the supernatant fluid. The lactate synthesis is increased, however. It is suggested that the permeability of the cell membrane is increased while dust particles are being phagocytosed, which may take several hours when the particles are fibrous, but that this does not imply cell damage.Treatment of chrysotile with acid, which leaves a silica surface, results in a product that reduces lactate synthesis, implying cytotoxicity. This change is counteracted by poly(2-vinylpyridine 1-oxide). The polymer does not affect the properties of the native chrysotile.Quartz particles that have been inhaled are phagocytosed by macrophages in the lung. The particles exert a cytotoxic effect and pulmonary fibrosis follows the death of macrophages. Macrophage cultures have been used to study the cytotoxicity of quartz and the ability of certain organic polymers to counteract its toxicity. Three tests that may be used are (1) the viability test, in which the uptake of acid dyes by macrophages is determined, (2) the estimation of lactic dehydrogenase (LDH) activity in the culture fluid, and (3) measurement of the rate of lactate synthesis by the cells.If a substance exerts a toxic effect on a cell, the cell membrane becomes more permeable so that acid dyes will pass into the cell and enzymes are released (Beck, 1968); decreased metabolism is shown by a decrease in the rate of lactate synthesis. An inert dust (e.g., corundum) affects viability and LDH values only slightly and it increases the rate of lactate synthesis because the work done in phagocytosing the particles increases the metabolic rate (Beck, 1968). Beck, Bruch, and Brockhaus (1963) showed that poly(2-vinyl-pyridine 1-oxide) (PVNO) reduced or even abolished the cytotoxic action of quartz particles on macrophage cultures.The published results on the effects of asbestos on cell cultures are confusing. Beck, Sack, and Bruch (1967b) found no cytochemical, optical or electron microscopical evidence of cell damage when chrysotile and other types of asbestos were incubated with mouse fibroblasts. Sack (1967), who used monolayer cultures of mouse fibroblasts (cell-line L), and peritoneal macrophages from the guinea-pig, and Beck (1970), who used alveolar macrophages from the guinea-pig, were unable to show any certain cytotoxic effects when asbestos was added although some differences were observed. Pernis, Vigliani, Marchisio, and Zanardi (1966) found no damage to mouse fibroblasts (cell-line L), KB-cells, and peritoneal macrophages of guinea-pigs, and no effect on the metabolic activity of the cells as judged by lactate production.However, Parazzi, Pemis, Secchi, and Vigliani (1968) found that, three methods (loss of fluorochromasia, LDH activity, and...

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. (1972). Brit. J. industr. Med., 29,[280][281][282][283][284][285][286] Comparison of effects on macrophage cultures of glass fibre, glass powder, and chrysotile asbestos. The effects on macrophage cultures of glass fibre, glass powder, and chrysotile asbestos are compared. Glass fibre behaves like chrysotile in producing an increase in cell membrane permeability in cultured macrophages. This is demonstrable by the increase in lactic dehydrogenase activity in the supernatant fluid. The metabolism, measured by lactate production, is not reduced as it is when quartz is phagocytosed. Glass powder behaves like the inert dust corundum, producing little change in the number of cells stained by erythrosin B and a small increase in lactate dehydrogenase activity, both being in the range of the control. There is an increase in lactate production as a result of higher metabolism due to phagocytosis. Dusts may produce two basic effects, namely a toxic effect and change in cell membrane permeability. A non-specific effect on the cell membrane due to the slow and sometimes incomplete process of ingestion of long fibres is probably a function of the morphology, particularly the length of the fibres. A primary specific effect induced by some dusts immediately follows contact with the cell membrane.Recent investigations have shown that asbestos fibres alter the permeability of the membrane of cells cultured in vitro. Koshi, Hayashi, and Sakabe (1968) demonstrated an increase in the acid phosphatase released from the cells into the culture medium when rat peritoneal macrophages were incubated with asbestos. Beck (1970) and Beck, Holt, and Nasrallah (1971) found that chrysotile asbestos added to cultures of alveolar or peritoneal macrophages increased the number of cells stained with erythrosin and increased the amount of lactic dehydrogenase (LDH) released into the culture medium.To determine whether the shape, the length or the chemical composition of the fibres is the factor influencing the permeability of the cell membrane, cultures of inacrophages were incubated with two types of fibrous material, chrysotile and glass fibre. In each case the permeability of the cell membrane was determined by estimating the percentage of cells that stained with erythrosin B and the LDH activity in the supernatant. The vitality of the cells was measured by the rate of lactate production. Controls were run with no addition of dust, with quartz powder (toxic), and with corundum powder (inert). Materials Chrysotile A high-grade Rhodesian chrysotile was opened in the mill of a dust tunnel (Holt, Mills, and Young, 1964).Glass fibre A dust was prepared in the same way from commercially available glass fibre. The sample ranged in length from I to 20 ptm and in diameter from 0-25 to 1 0 ,um. 280