1997 Volume 11 Issue 3 Pages 180-185
The structures of red cell saccharide chain were examined to analyze the abnormal agglutination of red cells in children with congenital chronic pure red cell aplasia (Diamond-Blackfan anemia = DBA) against peanut lectin (PNA, Arachis hypogaea). DBA was diagnosed within one month after birth. It was treated using corticosteroids without blood transfusion. A persistent positive reaction to PNA was seen in the red cells. The abnormal agglutination of the red cells to PNA disappeared after treatment with papain. Therefore, this abnormality may have contributed to sugar chain anomalies. PNA-reactive red cells were also seen in the control cord blood cells and Viblio cholerae (VC) -treated healthy control subjects, but were not observed in children with several types of anemia. The O-glycans were separated from glycoproteins in the PNA reactive red cell membranes by O-glycanase treatment. The O-glycans were subjected to HPLC and a single high saccharide chain peak was eluted after 14 minutes from VC-treated red cells, DBA patients and cord-blood red cells. The peaks in these O-glycans also passed through a PNA-absorbed column, while saccharide peaks were absent in healthy control and anemic patients. The distribution of PNA-reactive red cells in the total red cell population was analyzed by flow cytometry. With VC treatment, most red cells became PNA-positive but only ten percent was positive in DBA patients. The saccharide chain of the red cell membrane in DBA patients showed similar properties to the immature chain of cord-blood red cells or to the loss of sialic acid from O-glycan in VC-treated red cells in which a complete saccharide chain of sialic acid was lost. Therefore, abnormal saccharide chains expressed on red cell membranes may induce anemia in DBA patients.
