title: A novel method using formamide for the elution of antibodies from erythrocytes.
abstract: OBJECTIVE
  Accurate identification of antibodies that sensitize red blood cells (RBCs) involves dissociating them from RBCs using an in vitro elution method that does not alter their antigen-binding properties, and analysis of the eluates against a panel of RBCs.
  
  
  METHODS
  A method was developed that allowed efficient RBC antibody elution. Human polyclonal anti-D was used to sensitize Rh-positive RBCs, and known antigen-antibody disruptive reagents were tested using these RBCs. The best reagent conditions were optimized. Eluates made were tested and compared to results obtained with a glycine-acid-based commercial elution kit to determine efficacy. Patient samples that were positive with direct antiglobulin tests (DATs), and in vitro commercial antisera-sensitized RBCs representing clinically significant antibodies, were used for evaluating the new method.
  
  
  RESULTS
  The formamide method was efficient at removing antibodies from RBCs. The patient samples with a positive DAT had antibodies recovered with the same specificity when compared to the acid-based technique. The length of preparation time was similar for both formamide and acid-based methods. Results of testing the eluates made from reagent RBCs sensitized with commercial antisera were distinct with antigen-positive and -negative erythrocytes.
  
  
  CONCLUSIONS
  The formamide method compares well with acid techniques and may be an alternative choice of elution method.
authors.affiliation: National Institutes of Health, Warren Grant Magnuson Clinical Center, Department of Transfusion Medicine, Bethesda Maryland, USA. lcaruccio@mail.cc.nih.gov
authors.forename: L
authors.initials: L
authors.lastname: Caruccio
authors.forename: K
authors.initials: K
authors.lastname: Byrne
authors.forename: J
authors.initials: J
authors.lastname: Procter
authors.forename: D
authors.initials: D
authors.lastname: Stroncek
mesh_terms: D000372:Agglutination Tests; D004912:Erythrocytes / Q000276:immunology*; D005312:Fetal Blood; D005559:Formamides / Q000627:therapeutic use; D006801:Humans; D007106:Immune Sera; D007202:Indicators and Reagents; D007518:Isoantibodies / Q000276:immunology / Q000302:isolation & purification*; D008722:Methods; D012204:Rh-Hr Blood-Group System / Q000276:immunology; D018029:Rho(D) Immune Globulin
chemical_list: D005559:Formamides; D007106:Immune Sera; D007202:Indicators and Reagents; D007518:Isoantibodies; C061961:RHO(D) antibody; D012204:Rh-Hr Blood-Group System; D018029:Rho(D) Immune Globulin; C031066:formamide