0067 Immunity to Influenza B and Cross-reactivity to Pandemrix/pH1N1 in Narcolepsy

Abstract Introduction Narcolepsy type 1 (NT1) is caused by 85-95% hypocretin (HCRT) neuron loss due to a combination of genetic and environmental risk factors and associated with DQA1*01:02/DQB1*06:02 (DQ0602, 98%) and T cell receptor (TCR)gene AJ24/AJ28/BV4-2. Pandemic influenza A H1N1 (pH1N1) and Pandemrix vaccination in 2009-2010 induced NT1onset. Antigen specific T cell immune response in NT1 supports adaptive (auto)immunity against HCRT and Pandemrix/pH1N1. Despite this progress, the mechanism behind HCRT neuron loss and how the flu triggers a response against HCRT are unclear. Methods Anti-hemagglutination (HA) antibody was first measured using HA inhibition assay. Binding affinity of B/Victoria candidate peptides to DQ0602 was next tested using a competition binding assay. Antigen-DQ0602 restricted/reactive T cells were further isolated using tetramer DQ0602 and single-cell RNA sequenced with 10X. Lastly, TCR clones were transfected into Jurkat 76 for TCR activation by a certain peptide presented by DQ0602. Results Two independent studies of our laboratory and a Chinese group have shown a higher HAI titer against B/Brisbane/60/2008 in NT1. We detected reactive CD4+ T cells to a B/Victoria PB1 epitope that is homologous to Pandemrix/pH1N1 PB1 segment. In addition, we built a TCR repertoire a) restricted by HCRT and Pandemrix/pH1N1at baseline peripheral blood mononuclear cells (PBMCs) (n>430) and b) from single-cell RNA sequencing cerebrospinal fluid(CSF) samples (n>2,000), and found the identical activated TCR clones in both baseline and cultured PBMCs. Conclusion Our research showed influenza B plays a role in NT1 pathogenesis and potential cross-reactivity to PB1 between B/Victoria and Pandemrix/pH1N1. Support (if any) This project is supported by Wake Up Narcolepsy Research Grant.