1. From the Biochemistry and Immunology Department of Basic Medical Sciences (S.V.A., G.S.J.W., P.R.D., J.E.C.), St. George’s Hospital Medical School, Cranmer Terrace, London, UK; and Maternal and Fetal Research Centre (M.W., I.P.C., P.N.B.), St. Mary’s Hospital, Whitworth Park, Manchester, UK.