Long COVID is associated with female sex; Anti-NCAM1 autoantibodies are absent in patients with long COVID.

BACKGROUND: Long COVID is a condition that may arise following SARS-CoV-2 infection and is associated with a range of systemic complications. Autoantibodies are implicated in the pathogenesis of long COVID. However, the details of the pathogenic mechanisms undergone by these autoantibodies remain unclear. Neural cell adhesion molecule 1 (NCAM1) is the human protein with the highest sequence homology to the SARS-CoV-2 proteins. Previous in silico studies indicate that SARS-CoV-2 infection may induce the production of anti-NCAM1 autoantibodies. Thus, this study investigated the presence of anti-NCAM1 autoantibodies in individuals affected by COVID-19, including those with long COVID. METHODS: Serum samples were obtained from 173 individuals 3 months after SARS-CoV-2 infection. Among them, 63 were diagnosed with long COVID. A cell-based assay was used to assess all 173 serum samples for the presence of anti-NCAM1 autoantibodies. We also analyzed the clinical profiles of patients with and without long COVID to identify potential risk factors associated with long COVID. RESULTS: Anti-NCAM1 autoantibodies were not detected in any serum sample. The proportion of female patients in the long COVID group was significantly higher than that in the non-long COVID group. CONCLUSION: The results indicate that the production of anti-NCAM1 autoantibodies following COVID-19 is unlikely. Female sex is associated with higher risk of long COVID.