Absence of antimyelin antibodies and serum demyelinating factors in most patients with chronic inflammatory demyelinating polyradiculoneuropathy.

Patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) often respond to plasma exchange. One explanation for this is that circulating factors, such as antibodies or toxic factors, are removed from the serum. We studied CIDP nerves and CIDP sera for the presence of antibodies to myelin, Schwann cells and galactocerebroside, using immunofluorescence and enzyme-linked immunosorbent assays. On 1 of 28 CIDP nerve biopsies there was evidence of an IgG antibody bound to myelin. One of 57 CIDP sera had evidence of an antimyelin antibody, compared with 12 of 68 Guillain-Barré syndrome sera. We failed to find evidence of antibodies to Schwann cells or galactocerebroside in CIDP. The serum from only 1 of 11 patients showed demyelinating activity after direct intraneural injection. Thus these techniques do not demonstrate the presence of humoral factors to the tested antigens in the majority of CIDP patients. However, more sensitive methods may demonstrate antibodies to these antigens. Alternatively, CIDP may be associated with antibodies or factors toxic to other antigens, or else the response to plasma exchange may not be due to removal of a humoral factor.