Nat. Med. 11, 1059–1065; (2005); published online 11 September 2005; corrected 24 February 2006

In the version of this article initially published, the authors inadvertently misquoted a study as evidence that mouse NKT cells can express CD154 (ref. 29). Rather, the cited study concerned CD40-CD40L interactions in human NK cells. By misquoting this study, the authors also omitted an appropriate reference regarding prior evidence of CD40-CD40L interactions by murine NKT cells (Kitamura, H. et al., J. Exp. Med. 189, 1121; 1999). These errors have been corrected in the PDF version online.