Some bronchoalveolar lavage parameters and leukocyte cytokine release in response to intratracheal instillation of short and long asbestos and wollastonite fibres in rats.

We investigated the differences between the lavage parameters -- including tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) release by lavage leukocytes -- in control rats and in animals intratracheally instilled with short and long amosite and wollastonite fibres. These cytokines can play an important role in lung disease development after long-term exposure to some fibrous dusts. Short and long amosite and wollastonite fibres were intratracheally instilled in rats (1 mg/week) for ten weeks while saline was given to controls. To compare the harmful effects of these fibres, the number of leukocytes/ml of bronchoalveolar lavage (BAL), the number of alveolar macrophages (AM) per ml of BAL, AM:granulocyte (GR) ratios in lavage fluid, phagocytic activity and viability of AM, lactate dehydrogenase (LDH), acid phosphatase (AcP), and TNF-alpha and IFN-gamma release by lavage leukocytes were investigated 3 months after the first intratracheal instillation. Compared with the controls, amosite short fibres significantly decreased the numbers of AM/ml BAL, and increased their phagocytic activity and AcP release. Long amosite fibres significantly decreased the numbers of AM/ml BAL, increased the number of granulocytes depressed the phagocytic activity and viability of AM, and significantly decreased the levels of TNF-alpha and IFN-gamma in supernatants of cultured leukocytes. While wollastonite short and long fibre instillation did not significantly influence the parameters studied (except for a significantly increased number of leukocytes/ml BAL in wollastonite long fibres), amosite short and long fibres caused marked differences in these parameters, the long fibres being more effective.