Systematic Comparison of IgM and IgG ABO Antibody Titers by Using Tube and Gel Card Techniques and its Relevance for...

Although the determination of the ABO antibody titers is necessary for the decision-making in ABOincompatible (ABOi) kidney transplantations, various methods for the determination of the ABO antibody titers are being used. However, the absence of uniform standards makes their comparability far more difficult. Two of the most commonly used methods are the tube method and the gel card method. In this study, we systematically investigate to what extent these two methods affect the result of ABO antibody titers.

ABO antibodies were determined from plasmas of 90 donors (30 individuals each with blood group A, B, and O). Seven further donors with blood group A, B, and AB provided erythrocytes for the testing. A total of 360 ABO antibody titers were determined; 180 tests for each method, each with 90 determinations of immunoglobulin G (IgG) and immunoglobulin M (IgM) antibody titers. In addition, we also made a differentiation by blood groups to find out if and to what extent the blood groups have an impact on the results.

Our analysis shows that the choice of method has a highly significant (p < 0.0001) impact on the titer level of the ABO antibodies. The median values of ABO antibody titers determined by using the gel card method are two titer steps lower than the titers, which are determined when using the tube method. Moreover, our data shows that there are major differences in the ABO antibody titer level among the blood groups, regardless of the choice of methods.

We consider changing to the gel card method for determining the ABO antibody titers as a simple and effective way to achieve a standardized and uniform method. Here, too, the clinicians should be provided with sufficient information by the laboratories, in order to draw the right consequence from this change, while considering all the relevant data. As a consequence of this study, the transplant center of the University of Hamburg-Eppendorf paired a change from tube to gel card regarding the ABO antibody titer determination of ABOi kidney transplantations with an intensification of the preoperative target titer from ≤ 1:8 to ≤ 1:4.