Case report of anti-f(ce) antibody identified with unknown autoantibody from ABO discrepancy in a patient with liver cell carcinoma

The Rh blood type has 57 antigens, including D, C, E, c, and e. This blood type is clinically significant, alongside the ABO blood type. The anti-f(ce) antibody is an unexpected antibody that targets an antigen composed of the c and e antigens. We would like to report a case of the anti-f(ce) antibody discovered during an investigation of an ABO discrepancy. A 63-year-old man diagnosed with liver cell carcinoma was hospitalized for endoscopic variceal ligation due to esophageal varix. To prepare for the possibility of transfusion during the procedure, an ABO blood type test was conducted, resulting in B and O in cells and serum/plasma typing, respectively. The unexpected antibody identification test revealed the presence of the anti-f(ce) antibody. The Rh phenotype of the B cells used in the ABO serum/plasma typing test was determined to be ce. The anti-f(ce) antibody present in the patient's serum reacted with the B cells in the ABO serum/plasma typing test. To our knowledge, this is the first report of anti-f(ce) causing ABO discrepancy in Korea, and only the second reported case worldwide. We hope that our case report on the identification of the rare anti-f(ce) antibody from an ABO discrepancy will be beneficial for transfusion medicine laboratories.