Abstract
Red cells from 13 children with pure red cell aplasia (PRCA) were examined for reactivity of peanut lectin (PNA, Arachis hypogaea) and blood group antigen, and were analyzed for features of erythrocytic membrane glycoproteins. In several tests with PNA, a positive reaction was seen persistently with red cells from 5 children with congenital chronic PRCA, namely Diamond-Blackfan anemia (DBA) under treatment with corticosteroid without blood transfusion. In 5 reactive children with PRCA, the reaction was not affected by 0.05% polybrene but disappeared after treatment with papain. In these reactive patients with PRCA, no reaction was seen with lectins except for PNA nor polyagglutination was observed. From these findings, the reaction was considered to be caused by Th-activated red cells. The findings of SDS-polyacrylamide gel electrophoresis (SDS-PAGE) in these reactive children did not reveal any abnormality in the glycoproteins of red cell membranes. As to antigen activity of each blood group, similar to cord blood the positive reaction was seen for anti i antibody, while no abnormality was found for other antigens. With red cells from reactive DBA patients, positive reactions were seen in a ring-like shape by the method using FITC-labeled PNA. In addition, positive results were obtained in cytoplasma by the enzyme immunohistochemical staining with BFU-E colony-forming erythroblasts. These results suggest that the reactivity of red cells from DBA against PNA is attributable to abnormal structures of the surface sugar chains that are already present on the membranes at the stage of erythroblasts in bone marrow.
