[1] Univ Oxford, Weatherall Inst Mol Med, Oxford, England
[2] Univ London Imperial Coll Sci Technol & Med, Dept Immunol, London, England
[3] Univ Oxford, Nuffield Dept Orthopaed Surg, Oxford, England
[4] Univ Cambridge, Addenbrookes Hosp, Sch Clin Med, Cambridge CB2 2QQ, England