Red cell antigen stability in K3EDTA

Commercial blood grouping reagents are not approved for testing EDTA anticoagulated blood specimens that are more than 48 hours old. Many studies on the stability of blood group antigens in other anticoagulants have been reported, but none are available for EDTA. This study was undertaken to assess whether current commercially available blood grouping reagents give acceptable reactions with red cell antigens when the cells are stored for extended periods in EDTA We defined acceptable reaction strength to be 2 + (score 8). As expected, the A, B, and D reactions were very stable with red cells stored for 60 days. All antigens except Le^a exhibited 2+ (score 8) or greater reactions at day 14, and at day 21 only the Le^a, Fy^b, and e antigens were less than 2+. On day 60, twelve of twenty-one antigens tested still exhibited 2+ or greater reactions. This study shows that antigen reactivity for red cells collected and stored in EDTA is at least equal to that for clotted specimens. These red cells can be used for reliable antigen typing for at least 14 days, and even longer for most antigens. Immunohematology 1993;9:109.