Quantitation of mast cells in experimental allergic neuritis

The number and extent of degranulation of mast cells in the sciatic nerve have been determined in Lewis rats inoculated with bovine intradural root myelin to induce experimental allergic neuritis (EAN). No significant change in either the number of mast cells or the percentage of degranulated cells was observed before eight days post-inoculation (dpi). On day eight, however, there was a significant decrease in the number of detectable mast cells, and on day nine there was a significant increase in the percentage of degranulated cells. These changes immediately preceded the onset of clinical signs of EAN that occurred ten dpi. The number of detectable mast cells remained low throughout the acute stage of the disease, but by three weeks post-inoculation (wpi) there was a significant increase in the number of mast cells (or basophils) that persisted through 16 wpi. The increase in the percentage of degranulated mast cells also persisted through 16 wpi. These results suggest that mast cells participate in the development of EAN in the Lewis rat.