Nat. Immunol. 11, 701–708 (2010); published online 27 June 2010; corrected after print 13 August 2010

In the version of this article initially published, the author Shouxiong Huang (Department of Pathology and Immunology, Washington University, St. Louis, Missouri, USA) was not included. This author should be listed as author 15 (and affiliation 8). The error has been corrected in the HTML and PDF versions of the article.