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Interaction of mesothelial cells and asbestos in vivo

Asbestos fibres continually clear from the lung toward the pleura and lymphatics.
Short fibres may make this translocation more readily, but long fibres also move from the lung.
The rapidity of fibre translocation can be surprising. In rats, after intratracheal injection of chrysotile asbestos, fibres could be found in the pleura within 7 days and, in 1 of 3 rats
after inhalation of asbestos, fibres could be found in the pleural space 1 week after a 2 week exposure.
Free fibres or those within macrophages likely move with pleural liquid toward the lymphatic stomata, where liquid and protein are removed from the pleural space.
Here, it appears fibres cannot be completely removed and many of the longer ones accumulate and become concentrated in these discrete areas. After inhalation of asbestos in animals, asbestos fibres can be found adjacent to mesothelial cells, in the submesothelial space and occasionally within mesothelial cells themselves.
In human subjects exposed to asbestos in whom several different tissues were analysed, the concentration of asbestos fibres in pleural plaques or lymph nodes consistently exceeded that in the lung.
Indeed, fibre counts from the pleura may have been underestimated in the past, when the pleura was analysed as a whole.
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