Identification strategy for patients with ABO blood typing difficulties caused by IgM autoantibodies

The objective of this study was to investigate the characteristics of autoantibodies and cause of autoantibodies production and clinical blood transfusion strategies in the ABO blood group system by identifying and analysing 2 rare ABO blood group antigen-specific autoantibodies.

Blood group antigens and antibodies were detected via the conventional tube method, a gel microcolumn assay and the absorptionelution technique. The antibodies were characterized by direct antiglobulin tests and sulfhydryl reagent treatment of the plasma. ABO genotyping was performed using Sanger double-stranded sequencing of the ABO exons. Review the patient's medical records such as medical history and treatment history, and continuously monitor the ABO blood group.

The blood type of the first case was confirmed to be type A₁ by serological and molecular biological tests, with autoanti-A antibodies, the production of this autoantibody was associated with the disease itself; The blood type of the second case was type A₁B, with autoanti-B antibody, the production of this autoantibody was associated with the use of immune checkpoint inhibitors.

ABO blood group autoantibodies should be considered when antibodies against the A or B antigen are suspected in ABO reverse group typing after ruling out the possibility of alloantibodies, subtype antibodies and foreign antibodies. For patients with autoantibodies, appropriate blood products for transfusion should be selected based on the results of cross-matching tests, antibody thermal amplitude, and in-vitro hemolysis tests, and the transfusion process should be closely monitored.