Decrease in Intracellular Perforin Levels and IFN- Production in Human CD8 T Cell Line following Long-Term Exposure to Asbestos Fibers.

Although the tumorigenicity of asbestos, which is thought to cause mesothelioma, has been clarified, its effect on antitumor immunity requires further investigation. We previously reported a decrease in the percentage of perforin cells of stimulated CD8 lymphocytes derived from patients with malignant mesothelioma. Therefore, we examined the effects of long-term exposure to asbestos on CD8 T cell functions by comparing long-term cultures of the human CD8 T cell line EBT-8 with and without exposure to chrysotile (CH) asbestos as an model. Exposure to CH asbestos at 5 g/ml or 30 g/ml did not result in a decrease in intracellular granzyme B in EBT-8 cells. In contrast, the percentage of perforin cells decreased at both doses of CH exposure. CH exposure at 30 g/ml did not suppress degranulation following stimulation with antibodies to CD3. Secreted production of IFN- stimulated via CD3 decreased by CH exposure at 30 g/ml, although the percentage of IFN- cells induced by PMA/ionomycin did not decrease. These results indicate that long-term exposure to asbestos can potentially suppress perforin levels and the production of IFN- in human CD8 T cells.