Can blood group O red cells of donor origin acquire weak group A reactivity through serum A transferase of the recipient after bone marrow transplantation?

Background: Blood group A substance was detected on red cells of a patient who received a bone marrow transplant from a blood group O donor 3.5 years ago.

Materials and methods: Peripheral blood was investigated by conventional serological techniques, fluorescence in situ hybridisation, and polymerase chain reaction.

Results: All peripheral blood cells are of donor origin. Anti-A and not anti-A, B of blood group O individuals can be absorbed to the group O red cells of the patient.

Conclusion: We suppose that the patient's residual serum A transferase attaches the appropriate sugar to substance H on the red cell membrane to form substance A.