Nat. Immunol. 17, 505–513 (2016); published online 21 March 2016; corrected after print 26 August 2016

In the version of this article initially published, the middle initial (C) for the sixteenth author was incorrect. The correct author name should be Thomas M. Schmidt (and the corresponding initials in the Author Contributions section should be T.M.S.). The error has been corrected in the HTML and PDF versions of the article.