Peripheral polyneuropathies associated with monoclonal IgM. Antibody activity of monoclonal IgM and therapeutic implications.

Monoclonal IgM from patients with peripheral neuropathy react in nearly 80% of the cases with some components of myelin. The main target is myelin associated glycoprotein (50% of the cases); several types of glycolipids or gangliosides have been identified as the reactive antigen in the other cases. Anti-MAG IgM share little cross reactive idiotopes. Only primate antisera identified a combining site related public idiotope. In fact, these IgM use various light and heavy chains belonging to different variability subgroups. The preliminary results of an ungoing trial aimed to establish the benefit of plasmapheresis in these patients are discussed.