Anti-A/B immunoglobulin G subclass and C1q-binding antibody measurement using flow cytometry assay in ABO-blood-type-incompatible living-donor liver transplantation

Abstract

[Introduction] In ABO-blood-type-incompatible living-donor liver transplantation, it is important to remove as much blood group anti-A/B-IgG antibodies as possible prior to transplantation. However, there are rare cases suggesting the presence of hyperacute rejection, regardless of the titer of the blood group anti-A/B-IgG antibodies before transplantation. We have developed a new detection method for measuring the titers of blood group anti-A/B-IgG1–4 antibody subclasses to elucidate the immunological mechanism of the blood group anti-A/B-IgG antibodies. [Materials and Methods] The titers of the blood group anti-A/B-IgG antibodies of 20 recipients were measured by the conventional indirect antiglobulin method, and the titers of the total IgG, IgG1–4 subclasses, and C1q-binding antibody were determined by flow cytometry. [Results] From the results of this study, percentage distribution of the blood group anti-IgG1–4 antibody subclasses before liver transplantation was in the order of IgG2 (34.2%), IgG1 (29.1%), IgG3 (20.3%), and IgG4 (16.5%). It was considered that changes in the blood group anti-A/B-C1q-binding antibody and IgG1 and IgG3 were particularly important for the strong rejection in ABO-blood-type-incompatible living-donor liver transplantation. [Conclusion] Results of this study suggest that the above-mentioned detection methods may be useful in ABO-blood-type-incompatible living-donor liver transplantation to prevent humoral rejection.