Inflammation and Immunomodulation Caused by Short and Long Amosite Asbestos Samples

Abstract

In order to try and understand the processes underlying carcinogenesis in the peritoneal cavity following deposition of fibrous dusts, we instilled long and short fibre samples of amosite asbestos into the peritoneal cavity of mice and assessed some aspects of the inflammatory and immune response. In previous studies we have demonstrated that the long fibre sample causes mesotheliomas following intraperitoneal instillation while the short fibre sample is virtually inactive in this respect. There was a dramatic inflammatory response to a very low dose of long fibres and no effect with the same dose of short fibres. In animals immunised with Sheep Red Blood Cells, treatment with the long fibres caused a suppression of systemic humoral immunity, as assessed by the numbers of antibody-producing cells in the spleen; splenic T-cell responses were also depressed. The short fibre sample caused much smaller effects in inhibiting these immune responses. Long fibre amosite also caused a greater release of the cytokines Interleukin-1 and TNF from alveolar macrophages than did the short fibre amosite sample. Inflammation and immunosuppression may play a role in the pathogenic processes following peritoneal cavity deposition of fibres that lead to mesothelioma; cytokine release by macrophages may also play a role in these processes.