Effect of size of man-made and natural mineral fibers on chemiluminescent response in human monocyte-derived macrophages

Fiber size is an important factor in the tumorigenicity of various mineral fibers and asbestos fibers in animal experiments. We examined the time cour se of the ability to induce lucigenin-dependent chemiluminescence (CL) from human monocyte-derived macrophages exposed to Japan Fibrous Material stand ard reference samples (glass wool, rock wool, micro glass fiber, two types of refractory ceramic fiber, refractory mullite fiber, potassium titanium w hisker, silicon carbide whisker, titanium oxide whisker, and wollastonite). We determined how fiber length or width might modify the response of cells . We found that the patterns of time-dependent increase of CL (sigmoid type ) were similar for each sample except wollastonite. We observed a strong co rrelation between geometric-mean length and ability to induce CL in seven s amples > 6 mum in length over the time course (largest r(2) = 0.9760). Alth ough we also observed a close positive correlation between geometric-mean w idth and the ability to induce CL in eight samples < 1.8 mum in width at 15 min (r(2) = 0.8760), a sample of 2.4 mum in width had a low ability to ind uce CL. Moreover, the relationship between width and the rate of increase i n ability to induce CL had a negative correlation at 30-60 min (largest r(2 ) = 0.7473). Our Findings suggest that the release of superoxide from macro phages occurs nonspecifically for various types of mineral fibers depending on fiber length.