COMPARISON OF THE POLYETHYLENE-GLYCOL ANTIGLOBULIN-TEST AND THE USE OF ENZYMES IN ANTIBODY DETECTION AND IDENTIFICATION

Background: The polyethylene glycol indirect antiglobulin test for det ection of red cell antibodies was compared with a proven, highly sensi tive test system using papain. Study Design and Methods: Parallel, pro spective testing of 1508 samples with polyethylene glycol and with alb umin and papain evaluated the sensitivity and specificity of polyethyl ene glycol. Retrospective analysis of antibody specificities was perfo rmed for the 2 years before and the 2 years after the institution of p olyethylene glycol testing. Results: Of 1508 prospective screens, 53 ( 3.5%) had discordant results: 5 were positive only in polyethylene gly col and 48 were positive only in albumin and papain. Upon antibody ide ntification, the 5 samples that were positive only in polyethylene gly col showed 1 anti-D, 2 warm autoantibodies, and 2 false-positive resul ts. The 48 samples that were positive only in albumin and papain showe d 1 each of the following: anti-le(b); anti-P-1; anti-S; high-titer, l ow-avidity antibody; and cold autoantibody; there were 43 false-positi ve results. False-positive results totaled 12 (0.8%) with polyethylene glycol and 53 (3.5%) with albumin and papain. The retrospective analy sis of antibody specificity with polyethylene glycol showed a signific ant increase in the detection of and/or Fy(b) (p<0.0002) and Jk(b) (p< 0.0002) antibodies and a decrease crease in the detection of Le(a) and /or Le(b) antibodies (p<0.0002). Conclusion: Polyethylene glycol retai ned the high sensitivity of the albumin and papain, while significantl y lowering the number of false-positive results and decreasing the det ection of antibodies of doubtful clinical significance.