Antibodies to the Caspr1/contactin-1 complex in chronic inflammatory demyelinating polyradiculoneuropathy

Abstract Previous studies have described the clinical, serological and pathological features of patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) antibodies directed against paranodal proteins neurofascin-155, contactin-1 (CNTN1), contactin-associated protein-1 (Caspr1), or nodal forms neurofascin. Such are useful for diagnosis potentially treatment selection. However, targeting Caspr1 only Caspr1/CNTN1 complex been reported in few CIDP. Moreover, it is unclear if these belong to same pathophysiological subgroup. Using cell-based assays routine clinical testing, we identified sera from CIDP showing strong membrane reactivity when both CNTN1 were co-transfected (but not was transfected alone). Fifteen (10 male; aged between 40 75) cells enrolled characterization. The prevalence anti-Caspr1/CNTN1 1.9% (1/52) Sant Pau cohort, 4.3% (1/23) a German cohort acute-onset All fulfilled European Federation Neurological Societies/Peripheral Nerve Society (EFNS/PNS) definite diagnostic criteria Seven (47%) initially diagnosed Guillain-Barré syndrome due an acute-subacute onset. Six (40%) had cranial nerve involvement, eight (53%) neuropathic pain 12 (80%) ataxia. Axonal involvement acute denervation frequent electrophysiological studies. Complete response intravenous immunoglobulin observed, while most (90%) responded well rituximab. Enzyme-linked immunosorbent assay (ELISA) teased fibre immunohistochemistry confirmed complex. Weaker alone also detected 10/15 (67%). Sera 13 available testing by ELISA. samples reacted ELISA this enhanced added IgG subclasses investigated IgG4 predominant subclass 10 patients, IgG3 other three patients. In conclusion, display similar constitute single subgroup within syndrome. These likely target primarily Caspr1-only ELISA, but optimal