CHANGES IN ABH ANTIGEN EXPRESSION ON RED-CELLS DURING IN-VIVO AGING -A FLOW CYTOMETRIC ANALYSIS

Background: During aging of red cells they undergo a multitude of phys ical and chemical changes. Study Design and Methods: Age-dependent cha nges in the expression of ABH major blood group antigens on red cells were studied in a two-variable flow cytometric analysis. The expressio n of the antigens was measured after staining with fluorescence antibo dies (for A and B) or lectin (for H). Cell age was related to size as measured by forward light scattering. Aging senescent cells are smalle r and have low forward light scattering properties. Results: The resul ts indicated that, within a given population, the A and/or B and H ant igens decreased with the decrease in forward light scattering (i.e., i ncrease in age), but A and B antigen expression decreased to a greater extent than did H. Conclusion: During aging, red cells lose the antig ens of the major blood groups, but the degree of this loss is related to the fact that these antigens are located on the cell surface.