title: Antibody removal before ABO-incompatible renal transplantation: how much plasma exchange is therapeutic?
abstract: BACKGROUND
  ABOi transplantation is an accepted method of expanding the kidney donor pool but there is little analysis of the protocols used. We established an ABOi programme utilising leukocyte depletion, tacrolimus, TPE and IvIg. There are few reports in the literature on the success rates of antibody removal protocols or relating to patients in whom antibody removal fails. The purpose of this study was to define the likelihood of achieving transplantation depending on ABO antibody titers.
  
  
  METHODS
  56 patients entered our ABOi program. Data were analysed to determine the likelihood of achieving transplantation, ABO antibody titre prior to antibody removal and amount of TPE required to achieve transplantation. The median antibody titer was 1:64 (Range 0-1:1024). Transplantation proceeded when the ABO titer reached ≤1:4.
  
  
  RESULTS
  51/56 (91%) patients achieved transplantation after 8.3±5 TPE. Five patients with high ABO titers were not transplanted despite extensive TPE. The number of TPE required to reach an ABO titer of ≤1:4 correlates best with pre-treatment IgG titers.
  
  
  CONCLUSIONS
  This is the first study to demonstrate a cut off titer for entry in to the ABO incompatible program using the relationship between ABO titer and amount of TPE required to reach transplantation. We now tailor the antibody removal protocol prior to transplantation and have introduced a cut-off entry titer to the program (≤1:256), because of the unacceptable risk of exposing patients with higher titers to long-lasting immunosuppression and costly, prolonged, courses of TPE without the guarantee of successful transplantation. Patients whose ABO titer exceeds the cut-off are counselled and offered alternative routes to transplantation.
authors.affiliation: Imperial Kidney and Transplant Centre, Hammersmith Hospital, Du Cane Road, London W12 0HS, United Kingdom. c.lawrence@doctors.net.uk
authors.forename: Christopher
authors.initials: C
authors.lastname: Lawrence
authors.forename: Jack W
authors.initials: JW
authors.lastname: Galliford
authors.forename: Michelle K
authors.initials: MK
authors.lastname: Willicombe
authors.forename: Adam G
authors.initials: AG
authors.lastname: McLean
authors.forename: Mary
authors.initials: M
authors.lastname: Lesabe
authors.forename: Fiona
authors.initials: F
authors.lastname: Rowan
authors.forename: Vassilios
authors.initials: V
authors.lastname: Papalois
authors.forename: Fiona
authors.initials: F
authors.lastname: Regan
authors.forename: David
authors.initials: D
authors.lastname: Taube
mesh_terms: D000017:ABO Blood-Group System / Q000276:immunology*; D000328:Adult; D001787:Blood Group Incompatibility; D005260:Female; D006084:Graft Rejection; D006085:Graft Survival; D006801:Humans; D007518:Isoantibodies / Q000097:blood*; D016030:Kidney Transplantation / Q000401:mortality; D008297:Male; D008875:Middle Aged; D010951:Plasma Exchange; D014184:Transplantation, Homologous
chemical_list: D000017:ABO Blood-Group System; D007518:Isoantibodies