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Fiber size is an important factor in the tumorigenicity of various mineral fibers and asbestos fibers in animal experiments. We examined the time course of the ability to induce lucigenin-dependent chemiluminescence (CL) from human monocyte-derived macrophages exposed to Japan Fibrous Material standard reference samples (glass wool, rock wool, micro glass fiber, two types of refractory ceramic fiber, refractory mullite fiber, potassium titanium whisker, 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 correlation between geometric-mean length and ability to induce CL in seven samples> 6 µm in length over the time course (largest r² = 0.9760). Although we also observed a close positive correlation between geometric-mean width and the ability to induce CL in eight samples < 1.8 µn in width at 15 min (r² = 0.8760), a sample of 2.4 µm in width had a low ability to induce CL. Moreover, the relationship between width and the rate of increase in ability to induce CL had a negative correlation at 30-60 min (largest r² = 0.7473). Our findings suggest that the release of Superoxide from macrophages occurs nonspecifically for various types of mineral fibers depending on fiber length. Key words: fiber length, glass wool, macrophage, man-made mineral fibers, micro glass fiber, reactive oxygen species, refractory ceramic fiber, rock wool, silicon carbide whisker, Superoxide. Environ Health Perspect 109:1033-1038 (2001). [Online 27 September 2001] http://ehpnetl.niehs.nih.gov/docs/2001/109pl033-1038ohyama/abs tract.html [ABSTRACT FROM AUTHOR]

A significant increase in the CD38+ population among T lymphocytes has been observed in human immunodeficiency virus type 1 (HIV-1)-infected carriers. We previously reported a higher replication rate of T-tropic HIV-1 in the CD4+CD38+CD62L+ than CD38− subset under conditions of mitogen stimulation after infection. Here, we revealed a similarly high susceptibility in the CD38+ subset on culture with conditioned medium containing Th2 cytokine, interleukin (IL)-4 that was produced endogenously from this subset on stimulation with mitogen or anti-CD3 antibody for 3 days. The contribution of IL-4 to the upregulated production of virus in the CD38+ subset was confirmed by culture of this subset with recombinant human IL-4. In contrast, the rate of replication in the CD38− subset was not augmented in the conditioned medium from either subset or with IL-4. However, there were no differences in the surface expression of IL-4 receptor or HIV-1 receptors CD4 and CXCR4 between the two subsets. Thus, the CD4+CD38+CD62L+ subset comprises a specific cell population secreting endogenous Th2 cytokine that contributes to the efficient production of T-tropic HIV-1 through upregulation at a certain stage of the viral life cycle, probably after the adsorption step. [Copyright &y& Elsevier]