Anti-H antibody of unusually high titer showing variable reactivities against group A red cells and broad thermal amplitude in a patient with lymphoma

We report a case of a patient with high titer anti-H antibody showing broad thermal amplitude and variable reactivities against group A red cells. A 62-year-old Korean female was diagnosed with diffuse large B cell lymphoma involving multiple organs. Her ABO/RhD type was A+ and her genotype was ABO*A.01.01/ABO*O.01.02. Antibody screening test (AST) and antibody identification test (IDT) were strongly positive for all reagent cells. Anti-human globulin (AHG) test revealed an antibody titer of 1:256 for 37?°C phase and trace positivity for poly- and mono-specific C3d. Reactivity was stronger for O+ red cells than that for A+ red cells across all temperatures tested (4?°C, room temperature (RT) and 37?°C). This was also found for AHG phase. Anti-IH was ruled out based on agglutination of O+ cord cells (CCs). Antibody was determined as IgM anti-H after DTT treatment. Three batches of 10 A+ red cells from random donors were tested with three consecutive serums for crossmatching using tube method. Interestingly, out of thirty A+ red cells tested, 20 cells at RT, 11 cells at 37?°C and 11 cells in the AHG phase showed reactivity of greater than 2+. The patient was transfused with 6 units of packed RBCs subsequently. Chemotherapy (R-CHOP regimen) and Helicobacter pylori eradication were then started. Her antibody titer gradually decreased following such treatment. In conclusion, we identified a case of patient with high titer anti-H with broad thermal amplitude, suggesting that anti-H antibodies might need to be considered for cases with pan-agglutination in AST and IDT.