Variability in immunohistochemistries of IgM M-proteins binding to sulfated glucuronyl paragloboside

Serum IgMs from 4 of 12 patients with polyneuropathy and IgM M-proteins that bind to sulfated glucuronyl paragloboside (SGPG) strongly immunostained the human peripheral nerve myelin (group A), whereas those from the other eight patients strongly immunostained the cytoplasm of the Schwann cells surrounding the myelin sheath with only weak staining of the myelin (group B). Strong immunostaining of peripheral myelin by IgMs from group A patients may be due to the strong cross-reactivities against P0 and peripheral myelin protein-22 (PMP-22), which are localized in compact myelin. Only three patients (all in group B) showed some response to the immunotherapies. Weak reactivities to P0 and and PMP-22 might indicate the possibility of improvement after the immunotherapies.