[The interaction between cells and fibrous dusts (author's transl)].

The shape of fibrous dust particles is an important factor for the biological effects in cell cultures. The fibres elicit a special mechanism of incorporation which is dependent on their length and diameter but independent of their chemical composition. Fibres with a length less than 5 mum are phagocytized rapidly and completely by the cells, comparable to granular dust particles or milled fibres. Phagocytosis of long inorganic fibers is delayed and/or remains incomplete. Incomplete incorporation of the fiber causes a localized discontinuity in the cell membrane. There results continuous liberation of intra-cellular enzymes, which is compensated by an increasing glycolytic metabolism. The interaction between cell and fibre means a chronic irritation which is discussed as a factor in tumour induction. Fibrous dusts, e.g. asbestos and glass fibers, induce the formation of polykaryotic giant cells by way of fusion; asbestos possibly also causes the interspecific fusion of cells. There are indications that in the process of asbestos-induced cell fusion integrated virus genomes are activated and infectious viruses are released. There seems to be a causal relationship between the fibrogenic and carcinogenic effects of inorganic dusts and their shape, i.e. their length and diameter, regardless of their chemical composition. Thus the fibrogenic and carcinogenic effect is limited by a minimal length and a maximal diameter. The findings are discussed with regard to the air burden of fibrous dusts and their implications for human health.