A member of the B7-DC XAb investigative team, Dr. Suresh Radhakrishnan, who was involved in or had access to all of the work on this subject, was found, in a formal investigation, to have engaged in scientific misconduct in unpublished experiments involving the B7-DC XAb reagent.This finding of misconduct and our inability to reproduce key findings using blinded protocols has undermined our confidence in our published reports.Therefore, this article needs to be retracted.