To investigate the detecting method and clinical characteristics of anti-nodal/paranodal antibodies in chronic inflammatory demyelinating polyradiculopathy.

Serum samples were collected from 212 patients with chronic inflammatory demyelinating polyradiculopathy who were admitted to Huashan Hospital of Fudan University or from other clinical centers from January 2018 to July 2021. Autoantibodies (anti-NF155, anti-NF186, anti-CNTN1) and IgG subtypes were detected with cell-based assay. According to the test results, patients were divided into anti-NF155 positive group, anti-NF186 positive group and anti-CNTN1 positive group, clinical characteristics of patients in each group, including limb weakness, superficial sensation and proprioception, tremor, cerebrospinal fluid protein level, brachial plexus magnetic resonance (MRI) were retrospectively analyzed and compared.

A total of 23 patients (10.8%,23/212) were positive for anti-NF155 antibody, 12 (5.7%,12/212) for anti-NF186 antibody, and 4 (1.9%,4/212) for anti-CNTN1 antibody. IgG 4 was the predominant subtype in anti-NF155 and anti-CNTN1 groups. In the anti-NF186 group, all cases were IgG positive and antibody subtypes could be detected in 4 cases (4/12). In anti-NF155 group, 23 patients (100%,23/23) had limb weakness and deep sensory disturbance, 19 patients (82.6%,19/23) had superficial sensory disturbance, 22 patients (95.7%,22/23) were symmetrically involved, 18 patients (78.3%,18/23) showed tremor, 19 patients (19/19) showed abnormal in brachial plexus MRI. In anti-NF186 group, 12 patients had limb weakness (12/12), 9 patients (9/12) and 6 patients (6/12) had superficial sensory disturbance and deep sensory disturbance respectively, 8 patients (8/12) were asymmetrically involved, and only 1 patient (1/12) showed tremor, 1 (1/7) showed abnormal brachial plexus MRI. In anti-CNTN1 group, 4 cases showed symmetrical limb weakness and sensory disturbance, 3 patients had tremor, and four patients showed brachial plexus MRI abnormality. There were statistically significant differences in onset age, proprioception, tremor and MRI abnormalities of brachial plexus among the 3 groups (P<0.01).

The clinical characteristics of CIDP patients with anti-NF155, anti-NF186 and anti-CNTN1 antibodies are different. Screening anti-nodal/paranodal antibodies is of great significance for accurate diagnosis and treatment of patients with peripheral neuropathy.

Polyradiculoneuropathy, chronic inflammatory demyelinating; Autoantibodies; Contactin 1; Laboratory techniques and procedures