DEVELOPMENT OF A CARBOHYDRATE ANTIGEN DURING STORAGE OF RED-CELLS

Background: Changes in surface antigens during the aging of red cells led to the expression of epitopes that can induce an immune response. Recently, irregular antibodies detected in the sera of two patients ag glutinated in vitro aged red cells. Study Design and Methods: The agin g of red cells during storage was examined by flow cytometric analysis using fluorescein isothiocyanate-labeled lectins, fluorescein isothio cyanate-labeled anti-human IgG, and fluorescein isothiocyanate-labeled IgM. Results: Red cells stored for 1 day and 21 days exhibited no dif ference in the binding of wheat germ agglutinin, Ulex europaeus agglut inin, or concanavalin A, Only soybean agglutinin showed increased bind ing to old red cells. IgM antibodies present in the sera of two patien ts induced strong agglutination of stored red cells, but not of fresh red cells of the same or compatible ABO blood groups. The binding of t hese antibodies did not involve known red cell antigens and could be s ignificantly inhibited by galactose and mannose in a dose-dependent ma nner. Staining of red cells with sera from both patients indicated tha t the antibodies recognized the same structure on stored red cells. Th e number of binding sites on red cells stored for 21 days was between 7,000 and 10,000 per cell. Conclusion: These results demonstrate that, during storage of red cells, gradual expression of galactosyl residue s on the red cell membrane occurs.