. Author manuscript; available in PMC: 2020 Jul 20.
Published in final edited form as: Nat Immunol. 2020 Jan 20;21(2):178–185. doi: 10.1038/s41590-019-0578-8
Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use:http://www.nature.com/authors/editorial_policies/license.html#terms