Characterization of anti-D monoclonal antibody reagents based on their reactivity with the weak D phenotype

Background: Anti-D monoclonal antibody (MoAb) reagents have improved D typing in routine tests. However, they exhibit a wide range of reactivity with the weak D phenotype depending on the characteristics of the different MoAbs used. We analyzed the reactivity of immunoglobulin (IgM) anti-D by cluster analysis to characterize MoAb that have similar reactivities with the weak D phenotype. Study Design and Methods: We used 36 consecutive samples with weak D phenotype in routine testing and determined their reactivity with different IgM and IgG anti-D MoAbs. The samples were characterized as belonging to a weak D type or category using commercial molecular biology kits. Results: The various anti-D MoAbs showed a wide grade of reactivity with the weak D samples. Similarities and dissimilarities in the behavior of the anti-D MoAbs with the weak D phenotype samples were detected with cluster analysis and the multidimensional scaling analysis. These analyses indicated different families of MoAbs characterized as having a high degree of homogeneity in their reactivity with the weak D phenotype. Between these MoAb families, the most effective at reacting with the weak D phenotype were RUM-1 and 175-2. CONCLUSIONS: The results show that it is possible to classify the anti-D MoAbs on the basis of their reactivity with the weak D phenotype. This provides information about different MoAbs' properties on the basis of their belonging to a given of anti-D family. © 2008 American Association of Blood Banks.