Background: Isohemagglutinins (anti-A and anti-B) mediate hemolytic transfusion reactions, antibody-mediated rejection of solid-organ transplants, and delayed engraftment after stem cell transplant. However, quantification of isohemagglutinins is often labor intensive and operator dependent, limiting availability and interfacility comparisons. We evaluated an automated, solid-phase and agglutination-based antibody titer platform versus manual gel testing.
Study design and methods: Plasma samples were obtained from 54 randomly selected patients. Titers were determined by our laboratory's standard assay (manual dilution followed by manual gel testing) and were compared to results obtained on a fully automated blood bank analyzer (Galileo NEO, Immucor). The analyzer determined immunoglobulin G (IgG) antibodies using solid-phase and immunoglobulin M (IgM) antibodies by direct hemagglutination.
Results: Isohemagglutinin titers obtained by manual gel versus the automated assay generally (>80%) agreed within one doubling dilution, and always (100%) agreed within two dilutions. Among O samples, the gel titer and the highest titer obtained with the automated assay (either IgG or IgM) were similar in paired, nonparametric analysis (p = 0.06 for anti-A; p = 0.13 for anti-B). Gel titers from group A and group B patients were slightly higher than the highest titer obtained using the automated assay (p = 0.04 for group A; p = 0.009 for group B), although these differences were within the accepted error of measurement.
Conclusion: Manual and automated methodologies yielded similar isohemagglutinin titers. Separate quantification of IgM and IgG isohemagglutinins via automated titration may yield additional insight into hemolysis, graft survival after ABO-incompatible transplantation, and red blood cell engraftment after ABO-incompatible stem cell transplant.
© 2020 AABB.