[1] Univ Penn, Perelman Sch Med, Philadelphia, PA 19104 USA
[2] Univ Penn, Perelman Sch Med, Immunol Grad Grp, Philadelphia, PA 19104 USA
[3] Univ Michigan, Ann Arbor, MI 48109 USA
[4] Kantonsspital St Gallen, Inst Immunobiol, St Gallen, Switzerland
[5] Genentech Inc, San Francisco, CA 94080 USA