The Effect of Aramid and Metaphosphate Fibers on Macrophage Viability and Function

Abstract

This study was designed to evaluate the cytotoxicity of a number of asbestos substitute fibers on primary rat alveolar macrophages (AMs) and a mouse macrophage-Iike cell line (J774A.1) in vitro. Following 24- and 48-hour incubations, the cells were observed under phase contrast microscopy for changes in cell morphology and cell viability was assessed using trypan blue exclusion. A viability index (VI) was calculated to reflect changes in both cell number and cell viability. All of the materials studied produced a concentration-dependent reduction in VI. In addition, both Kevlar and calcium sodium metaphosphate (CSMP) fibers produced a concentration- dependent release of lactate dehydrogenase (LDH) from primary AMs. Finally, no chemotaxis was observed in response to either Kevlar or CSMP fiber alone, but both fibers stimulated measurable concentration-dependent chemotaxis when incubated with AMs. These results suggest that all of the materials were cytotoxic to AMs in vitro in the form and at the concentrations (25, 250 µg/mL) used in this study and can affect AM function. What effect these materials have on the human health remains to be determined.