Unexpected occurrence of anti-B antibodies in a patient with A2B blood group: a case report and review of literature.

BACKGROUND

The ABO blood group system categorizes human blood according to the inherited characteristics of erythrocytes, which are defined by the presence or absence of antigens A and B located on the surface of red blood cells. In the absence of these antigens, the body produces natural antibodies.

CASE PRESENTATION: In this case report, we present a 42-year-old man of Iranian (Persian) ethnicity who was a blood donor at the Arak transfusion center. Forward and reverse typing showed a discrepancy, with AB as the cell type and O blood group as the back type results.

CONCLUSION

This report shares our experience of unexpected anti-A and anti-B antibodies presence in AB blood group. Finally, it was discovered that the patient has an A2B blood group with clinically insignificant anti-A1 antibodies. The reason behind the occurrence of B antibodies in this case is still unknown but can be considered an acquired B phenomenon. To the best of our knowledge, this is the first report of anti-B antibodies in a patient with an A2B blood type in Iran.