1 Title: Composition and structure of synaptic ectosomes exporting antigen receptor linked to functional CD40 ligand from helper T-cells. Authors: David G. Saliba 1† ‡, Pablo F. Céspedes-Donoso 1† , Štefan Bálint 1† , Ewoud B. Compeer 1 , Salvatore Valvo 1 , Kseniya Korobchevskaya 1 , Viveka Mayya 1 , Yanchun Peng 2,3 , Tao 5 Dong 2,3 , Maria-Laura Tognoli 4 , Eric O’Neill 4 , Sarah Bonham 5 , Roman Fischer 5 , Benedikt M. Kessler 5 , and Michael L. Dustin* 1 Affiliations: 1. Kennedy Institute of Rheumatology, Nuffield Department of Orthopedics, Rheumatology and Musculoskeletal Sciences, The University of Oxford, Oxford, UK 10 2. MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, Oxford University 3. Chinese Academy of Medical Science Oxford Institute, Nuffield Department of Medicine, Oxford University 4. Dept of Oncology, The University of Oxford, Oxford, UK 15 5. Discovery Proteomics Facility, Target Discovery Institute, Nuffield Department of Medicine, The University of Oxford, Oxford, UK *Corresponding author: michael.dustin@kennedy.ox.ac.uk †Equal contributions ‡ Current address: Centre for Molecular Medicine and Biobanking, University of Malta, Msida, 20 Malta. . CC-BY 4.0 International license certified by peer review) is the author/funder. It is made available under a The copyright holder for this preprint (which was not this version posted April 9, 2019. . https://doi.org/10.1101/600551 doi: bioRxiv preprint