The effects of colophony fume on respiratory tract immunology. Final report on Health and Safety Executive project 1/LMD/126/239/88

The inhalation of colophony fumes, as produced, for example, in soft soldering, can lead to the development of respiratory symptoms and occupational asthma in exposed workers. It is not clear whether these effects of colophony are due to an inflammatory action, immune responses to colophony fume components, a pharmacological action, or some combination of these effects.Using an animal model we studied the effects of fumes from heated colophony or solder wire on the respiratory tract and on the immune responses to intranasally-administered ovalbumin. It was found that up to 35 daily, 70-minute exposures to colophony or solder fume had no overt effects on upper.or lower respiratory tract histology and that both numbers and types of cells recovered’by bronchoalveolar lavage were unchanged. In vitro production of the pro-inflammatory cytokine tumour necrosis factor (TNF) by cells recovered by lung lavage was also unaffected by In vivo exposure to fume. Other negative findings were that immune responses to colophony could not be detected in fume-exposed animals and that IgG and lymphocyte responses to ovalbumin were unaltered by exposure to fumes. However, there was, on average, a 40% reduction in serum concentration of IgE antibodies to ovalbumin following 35 exposures to fume.In in vitro studies it was found that colophony was toxic to cells of the human lung epithelial line A549 causing some detachment from culture wells and lysis at a concentration of 50 ug/ml and 80% lysis at 150 ug/ml. Fume recovered from the exposure chamber was even more toxic in this assay. Four different types of colophony did not activate human serum complement.Further work is required: (a) to explain the contrast between the in vitro toxicity of colophony and the lack of effect on the respiratory tract in vivo, (b) to study the immune response to components in colophony other than resin acids, and (c) to see if colophony has any pharmacological effects on cells of the respiratory tract.