Plasma blood group glycosyltransferase activities after bone marrow transplantation

Human blood groups (ABO) are known to be determined by the terminal glycosyl residues attached to common carbohydrate chains of the red cell surface. N-acetylgalactosaminyltransferase (A-enzyme) in blood group A persons and galactosyltransferase (B-enzyme) in blood group B persons are responsible for producing A and B substances on the red cell surface, with both enzymes absent in blood group O persons. The plasma transferase (A - and B-) activity was assayed after the complete replacement of the bone marrow of patients with acute leukemia or aplastic anemia by transplantation bone marrow from donors with ABO blood group differing from the recipient. The patient's blood type completely changed from the recipient's type to the donor's type. However, the A- and B-enzyme activities of the patients changed only slightly after bone marrow transplantation. The results indicate that most of the A- and B-enzymes in the circulatory plasma is not derived from the bone marrow, lymphoid, or macrophage tissue. Other tissues must be the primary source of the enzymes in plasma.