[Isoagglutinins after bone marrow transplantation with minor ABO incompatibility].

Sera of 22 patients after BMT with blood group change from A to 0 were investigated. Early after BMT 59% of the patients developed a temporary anti-A whereas late after BMT none of the patients tested showed isoagglutinins against A even though the red blood cells were of type 0 and anti-B was present. The onset of these anti-A isoagglutinins correlated with production of leukocytes by the donor BM and is regarded as a sign of GvHR. Late after BMT a permanent immunological tolerance to the A antigen of the recipients' old blood group seems to exist.