The "frustrated phagocytosis" logo shown larger here is the last frame of an animation of the process by which a lung macrophage attempts unsuccessfully to envelope a long fiber. Ordinary particles and short fibers may be engulfed completely by a lung macrophage (shown in green), whereas a sufficiently long fiber (black) is too long to be successfully engulfed. The fiber is the only shape that can be inhaled to the deep lung by virtue of its thin diameter, but is too big to be enveloped by the lung macrophage by virtue of its length. This unsuccessful attempt leads to the leakage of potent enzymes (shown in red) from the interior of the cell onto the surface of the lung with consequent lung damage that is thought to lead to lung disease including cancer. * Such diseases do not develop if the long fibers can be removed rapidly from the deep lung by dissolution in the lung fluid.§
* Osinubi, Gochfeld, and Kipen, "Health Effects of Asbestos and Nonasbestos Fibers", Environ. Health Perspec. 108, 665-664 (2000) and references cited therein.
§ Churg, Wright, Bilks, and Dai, "Pathogenesis of fibrosis produced by asbestos and man-made mineral fibers: What makes a fiber fibrogenic?". Inhalation Toxicology 12 (Suppl. 3), 15-26 (2000).