[A case of refractory anemia with excess of blasts (RAEB) having weakened expression of B blood group antigen].

A 52 year-old male was admitted to our hospital with the complaint of the hypochondrial pain after meal in February 1989. He was diagnosed to be RAEB and to have common bile duct stone. His red blood cells (RBC) could not be agglutinated with anti-A, anti-B, or anti-A, B. The agglutinability of the cells to Ulex europaeus (anti-H) was the same to the normal type B RBC, and his serum contained anti-I, anti-E, and anti-c. In his saliva, both B and H antigens were detected. The glycosyl B transferase in his serum showed similar activity to that of normal individual with type B RBC. When his RBC were treated with normal type B transferase, the cells obtained the reactivity to anti-B but they agglutinated much weaker than the type O cells treated with the enzyme. These results indicated that the low agglutinability of his RBC could not be due to the low transferase activity but the qualitative or quantitative changes of the precursor molecules of the type B substance of the cells.