Evaluation of Erythrocytes Magnetized Technology for Measurement of ABO Isoagglutinin Titers.

A variation in the measurement of ABO antibody titer has been seen among different laboratories due to lack of standardization. In our study, we aim to evaluate automated ABO isoagglutinin titer measurements by erythrocytes magnetized technology (EMT) and compare with conventional tube technique (TT).  We performed ABO isoagglutinin titration on samples received in a reference laboratory during a period of 2 months. A total of 134 tests for immunoglobulin G (IgG) titer and 116 for immunoglobulin M (IgM) for anti-A or anti-B were included in the study. Samples were processed for ABO isoagglutination titers by both TT and EMT by QWALYS-3 (DIAGAST, France). Microsoft Excel was used to compile data, for all calculations, and to draw graphs and plots. The number and percentage of cases within ±1, ±2, or ±3 titer difference (TT-EMT) were calculated.  Median titers and their ranges obtained by EMT were higher or equal to those by TT for all IgM and IgG ABO-antibodies in all blood group (BGs), except anti-A IgM in (BG) O that was lower by EMT (32 [4:128]) than TT (48 [8:256]). One twenty one (121/134, 90.3%) cases of IgG titer showed an agreement by both methods (within ± one titer difference). One hundred seven cases (107/116, 92.2%) for IgM titer were within one titer difference by both the methods.  Results of titration by EMT-based automated instrument QWALYS-3 and conventional TT may vary by one titer dilution in the majority of cases. Use of consistent method for patient management is, therefore, advised.