Abstract: | A patient with blood group O died 8 h after an accidental transfusion of one unit of A1 erythrocytes. The admixture of group A red cells was not detected during postmortem serology. Paraffin-embedded autopsy material was studied by the indirect immunoperoxidase technique using monoclonal antibodies. Group A red cells were easily identified as circulating agglutinates in the larger vessels, in the capillary vessels of all organs examined, and as closely packed cell aggregations in the sinuses of the spleen. However, there was no clear evidence of erythrophagocytosis in the spleen or in liver. |