title: The clinical importance of flow cytometry crossmatch in the context of CDC crossmatch results.
abstract: BACKGROUND
  The complement-dependent microcytotoxicity crossmatch (CDCXM) is a standard method for evaluating the presence of preformed antibodies before transplantation. The flow cytometry crossmatch (FCXM) is more sensitive, but there is controversy regarding translation of its increased sensitivity to clinically relevant graft outcomes.
  
  
  METHODS
  We analyzed Organ Procurement and Transplant Network registry data for living and deceased donor kidney transplants performed in 1995 to 2009 after both CDCXM and FCXM testing. Transplants with negative CDCXM (CDCXM(-)) and with T-cell positive (T(+)), T-cell negative/B-cell positive (T(-)B(+)), or T- and B-cell negative (T(-)B(-)) FCXM results were included. Graft survival according to crossmatch results was compared by survival analysis.
  
  
  RESULTS
  Among patients transplanted with negative CDCXM (CDCXM(-)), deceased and living donor graft recipients with T(+) FXCM experienced significant absolute reductions in 5-year graft survival of 11.5% and 8.8% compared to those with T(-) FCXM (P < .0001). Compared to patients with FCXM(-)/CDCXM(-) deceased and living donor recipients with T(-)B(+) FCXM/CDCXM(-) had absolute reductions in 5-year graft survival of 9.6% and 7.6%, respectively (P < .0001). Upon multivariate adjustment with Cox regression, T(+) FCXM/CDCXM(-) deceased donor transplantation was associated with 51% higher adjusted relative risk of 1-year graft loss than FCXM(-)/CDCXM(-). Relative risks were more marked at 1 year for the T(+) groups but stronger in the 1- to 5-year interval for the T(-)B(+) groups.
  
  
  CONCLUSIONS
  Positive FCXM has important prognostic implications even when CDCXM is negative. Thus, positive FCXM should not routinely be dismissed as "overly sensitive" when CDCXM is negative.
authors.affiliation: Department of Surgery, HLA Laboratory, Saint Louis University, St. Louis, Missouri, USA.
authors.forename: R J
authors.initials: RJ
authors.lastname: Graff
authors.forename: P M
authors.initials: PM
authors.lastname: Buchanan
authors.forename: N
authors.initials: N
authors.lastname: Dzebisashvili
authors.forename: M A
authors.initials: MA
authors.lastname: Schnitzler
authors.forename: J
authors.initials: J
authors.lastname: Tuttle-Newhall
authors.forename: H
authors.initials: H
authors.lastname: Xiao
authors.forename: E
authors.initials: E
authors.lastname: Schadde
authors.forename: A
authors.initials: A
authors.lastname: Gheorghian
authors.forename: K L
authors.initials: KL
authors.lastname: Lentine
mesh_terms: D000906:Antibodies / Q000097:blood*; D001402:B-Lymphocytes / Q000276:immunology; D003601:Cytotoxicity Tests, Immunologic; D005434:Flow Cytometry; D006084:Graft Rejection / Q000276:immunology*; D006085:Graft Survival; D006650:Histocompatibility Testing / Q000379:methods*; D006801:Humans; D053208:Kaplan-Meier Estimate; D016030:Kidney Transplantation / Q000009:adverse effects*; D019520:Living Donors; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D012042:Registries; D018570:Risk Assessment; D012307:Risk Factors; D012680:Sensitivity and Specificity; D013601:T-Lymphocytes / Q000276:immunology; D013997:Time Factors; D009927:Tissue and Organ Procurement; D016896:Treatment Outcome; D014481:United States
chemical_list: D000906:Antibodies