[1] John Radcliffe Hosp, Natl Blood Serv, Oxford OX3 9DU, England
[2] Southmead Gen Hosp, Natl Blood Serv, Bristol BS10 5ND, Avon, England
[3] Norfolk & Norwich Univ Hosp NHS Trust, Dept Haematol, Norwich NR4 7UY, Norfolk, England
[4] Northampton Gen Hosp, Northampton NN1 5BD, England