Development of a carbohydrate antigen during storage of red cells

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 agglutinated in vitro aged red cells.

The aging of red cells during storage was examined by flow cytometric analysis using fluorescein isothiocyanate-labeled lectins, fluorescein isothiocyanate-labeled anti-human IgG, and fluorescein isothiocyanate-labeled IgM.

Red cells stored for 1 day and 21 days exhibited no difference in the binding of wheat germ agglutinin, Ulex europaeus agglutinin, or concanavalin A. Only soybean agglutinin showed increased binding to old red cells. IgM antibodies present in the sera of two patients induced strong agglutination of stored red cells, but not of fresh red cells of the same or compatible ABO blood groups. The binding of these antibodies did not involve known red cell antigens and could be significantly inhibited by galactose and mannose in a dose-dependent manner. Staining of red cells with sera from both patients indicated that the antibodies recognized the same structure on stored red cells. The number of binding sites on red cells stored for 21 days was between 7,000 and 10,000 per cell.

These results demonstrate that, during storage of red cells, gradual expression of galactosyl residues on the red cell membrane occurs.