1. Department of Immunology and Microbiology, The Scripps Research Institute , La Jolla , CA 92037 , USA
2. Center for Immunity and Immunotherapies, Seattle Children’s Research Institute , Seattle , WA 98101, USA
3. Department of Biochemistry and Molecular Biology, University of Texas Medical Branch , Galveston , TX 77555 , USA
4. Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch , Galveston , TX 77555 , USA
5. Institute for Stem Cell & Regenerative Medicine, University of Washington , Seattle , WA 98109 , USA
6. Department of Laboratory Medicine and Pathology, University of Washington School of Medicine , Seattle , WA 98101 , USA
7. Department of Pediatrics, University of Washington School of Medicine , Seattle , WA 98101 , USA