Asbestos fibres inhibit the in vitro activity of ymphokine-activated killer (LAK) cells from healthy individualsand patients with malignant mesothelioma

Abstract

SUMMARY Asbestos exposure is associated with an increased incidence of several malignances. including malignant mesothelioma (MM). This study evaluates the relationship between asbestos exposure and the in vitro generation and function of LAK cells, an immune effector cell population with powerful lytic activity against MM cells. Both serpentine (chrysotile) and amphibole (amosite and crocidolilc) forms of asbestos fibres suppress LAK cell generation, viability (by 5–11%, P < 0.02) and cell recovery (by 13.15%, P < 0.02). However, the LAK cells generated in the presence of the amphiboles were as effective as unexposed cells in lysing both standard tumour cell targets (K562, 56.4% lysis versus 61.5%. respectively, P > 0.5; NS; Daudi. 60.5% lysis versus 64.5%P > 0.5; NS). and MM tumour cell targets (mean of three MM cell lines 48.3%versus 46.3%. P > 0.5; NS), whereas the function of LAK cells generated in the presence of chrysotile was significantly reduced against three out of the five tumour cell targets tested (P < 0.03). In the presence of asbestos fibres, LAK cell function was reduced against all five tumour cell targets (P < 0.0l). irrespective of whether the cell donors were healthy individuals or patients with MM. NK cell activity was also suppressed (P < 0.0l). The serpentine form of asbestos, chrysotile, was significantly more suppressive of both effector cell functions than either of the amphiboles (P < 001). These findings suggest that asbestos exposure may suppress the function and in some instances the generation of immune effector cell mechanisms, thereby increasing the risk of disease and malignancy.