Objectives: We sought evidence that chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an autoimmune disease by studying cellular and humoral immune responses to peripheral nerve myelin proteins.
Methods: We studied 40 CIDP, 36 healthy control subjects (HC) and subjects with non-immune mediated neuropathies (other neuropathies, ON) for antibodies by ELISA and cellular responses by cytokine ELISPOT (INF-γ, IL-10) and ELISA (IL-17) to synthetic peptides representing P0, P2 and PMP22.
Results: Antibodies to P0, P2 or PMP22 peptides were detected in only a minority of CIDP, both not treated (nT-CIDP) and treated (T-CIDP). IgG antibodies to P280-105 were significantly more frequent in CIDP than in HC (4/30 versus 0/32; p<0.05) but the difference from ON (1/25) was not significant. In ELISPOT assays, IFNγ was detected at low frequency in CIDP and did not differ from HC or ON. In contrast, IL-10 responses against P21-85 were more frequent in nT and T-CIDP (7/24 and 3/16) than HC (0/36; p<0.001 and p<0.05, respectively). The production of IL-17 in cell culture supernatants was not increased.
Conclusions: Antibodies to non-conformational antigenic epitopes of myelin proteins rarely occur in CIDP. None of the myelin protein peptides elicited IFN-γ responses but P2 elicited IL-10 responses significantly more often in CIDP patients than in controls. This reactivity may be part of an antigen specific Th2 type pathogenetic or regulatory mechanism or represent a transitory epiphenomenon due to nerve damage. In our study P2 was the protein antigen most likely to be involved in the aberrant immune responses in CIDP.