Conventional tube agglutination with polyethylene glycol versus Red Cell Affinity Column Technology (ReACT): a comparison of antibody detection methods.

A procedure for antibody detection and identification that utilizes affinity microcolumns to isolate IgG antibodies in a gel matrix containing Protein G and Protein A was commercially available in recent years. We evaluated this method (ReACT, Red Cell Affinity Column Technology, Immucor Co., Norcross, GA) as an alternative to standard tube agglutination testing, in an effort to minimize subjectivity and increase consistency of antibody identification in our hospital blood banks. Although the ReACT kit was withdrawn from the market soon after completion of our study, the advantages and limitations of the procedure warrant consideration should a similar product be reintroduced. The performance of the ReACT method was compared to conventional antibody detection by a standard tube agglutination technique that uses polyethylene glycol (PEG) potentiator (Dominion Biologicals Ltd., Dartmouth, Nova Scotia, Canada). Of 685 serum or plasma samples that were screened for antibodies, 96 samples were found by the PEG procedure to contain clinically significant (n = 70) and insignificant antibodies (n = 26). In contrast, 48 of the samples were found by the ReACT procedure to contain clinically significant (n = 39) and clinically insignificant antibodies (n = 9). For the ReACT method, the sensitivity was 48.8% (95% CI = 37.8%, 58.0%) and the specificity was 99.6% (95% CI = 97.5%, 99.9%), compared to the PEG procedure. While the ReACT microcolumn system was designed to limit detection of clinically insignificant antibodies, this study documents a loss of sensitivity for detection of clinically significant antibodies.