Humoral antibodies in immune mediated neuropathy

Immune mediated neuropathy includes acute inflammatory demyelinating polyneuropathy (AIDP), chronic inflammatory demyelinating neuropathy (CIDN), paraproteinemic polyneuropathy (PPN) and Crow-Fukase syndrome (CFS). Serum antibodies as humoral immunity in patients with immune mediated neuropathy were measured by the method of immunoblots and ELISA. P0 protein, P2 protein, 170K-Mr glycoprotein and ganglioside (GGD) of human peripheral nerve myelin and MBP, myelin associated glycoprotein (MAG) of human central nerve myelin were used as antigens. In AIDP anti P2 antibodies were elevated significantly. However, anti MBP antibodies were also elevated in parallel. In PPN anti MAG antibodies were detected in 4 patients with IgM-M proteinemia and demyelinating neuropathy. High titers of anti MAG antibodies were also detected in the same 4 patients. Characteristic pathological findings of biopsied sural nerve were segmental demyelination with widening of the intraperiod line of the outer myelin lamella in all 4 patients. Positive rate of anti myelin antibodies were 23% in 23 cases with PPN. Anti 170K-Mr glycoprotein was detected only in one patient with IgM-M proteinemia, polyneuropathy and incurable dermatitis. Anti GGD antibodies were not detected in PPN or CFS. A few patients with GBS or CIDN have anti GGD antibodies in ELISA. It is well known that various antibodies to peripheral nerve myelin are detected in neuropathy, especially demyelinating state. The most important antigen established in this study in the pathogenesis of neuropathy is MAG. IgM monoclonal protein including anti MAG antibodies was absorbed by purified MAG completely. Anti 170K Mr glycoprotein was also absorbed by purified 170K-Mr glycoprotein. Role of humoral antibody to peripheral nerve myelin specific 170K-Mr glycoprotein remains to be solved.