Protection against experimental allergic neuritis with silica quartz dust.

Lewis rats sensitized against peripheral nervous system antigens can be protected against experimental allergic neuritis (EAN) by the intraperitoneal injection of silica quartz dust. Two doses of 200 mg silica given 8 and 11 days post-inoculation (dpi) protected against the development of both clinical and pathological disease. A single dose of 200 mg silica 8 dpi gave significant protection against clinical disease but all animals developed pathological signs. A single injection of 200 mg silica 11 dpi, after the onset of early signs, protected against further progression of disease. The protection was long lasting. Given the known toxic effects of silica for macrophages, these results would support the conclusion that macrophages function during the effector stage in the clinical and pathological expression of EAN in the Lewis rat.