U1 Small Nuclear Ribonucleoprotein Autoantibodies Reflect the Disruption of the Blood-Nerve Barrier in Guillain-Barré Syndrome.

We recently identified the U1 small nuclear ribonucleoprotein (U1-snRNP) antibodies in patients with Guillain-Barré syndrome (GBS), which is associated with the breakdown of the blood-nerve barrier (BNB). The objective of this study was to clarify the clinical significance of U1-snRNP antibodies in patients with GBS and its variants. We measured U1-snRNP antibodies using an enzyme-linked immunosorbent assay from the serum samples of patients with GBS (n = 106), Miller Fisher syndrome (MFS) (n = 24), and MFS/GBS overlap syndrome (MFS/GBS, n = 8). We compared the clinical characteristics of U1-snRNP positive and U1-snRNP negative GBS patients (n = 106). The cerebrospinal fluid (CSF)/serum albumin quotient (QALB)/QALBLIM [calculated as(age/15) + 4)] was calculated. The prevalence of U1-snRNP antibody positivity was 39% (41/106) in GBS, 0% (0/24) in MFS, and 50% (4/8) in MFS/GBS. The rate of U1-snRNP antibody positivity in the GBS and MFS/GBS groups was significantly higher than that in the MFS group. Levels of CSF proteins and QALB/QALBLIM were higher in U1-snRNP antibody-positive GBS than in U1-snRNP antibody-negative GBS among all GBS patients, as well as GBS patients with a preceding Campylobacter jejuni infection or AIDP. In conclusion, the U1-snRNP antibody-positive GBS group had a more severe breakdown of the BNB in U1-snRNP antibody-positive GBS patients than in U1-snRNP-negative GBS patients. The presence of U1-snRNP antibodies may be a clinical biomarker for predicting the progression of MFS to MFS/GBS.