Immunoglobulins induce increased myelin debris clearance by mouse macrophages

The present study investigated the effect of human immunoglobulins on migration and myelin phagocytosis by macrophages. Mouse sciatic nerves and macrophages were cocultured and treated with 1, 10 and 20 mg/ml immunoglobulins for 10 days in vitro. Numbers of invading macrophages, myelin density within the nerves and macrophage myelin load were determined in semithin sections. Human immunoglobulins lead to an increased myelin removal by macrophages as proven by a statistically significant higher myelin load of the macrophage cytoplasm when compared with untreated control macrophages. The results suggest that one possible action of immunoglobulins in demyelinating diseases is an improved clearance of lesional debris with the removal of myelin-associated inhibitory molecules.