Chemokine scavenging function and Duffy antigen expression in stored human erythrocytes. (A) A total of 10⁸ erythrocytes from a volunteer were incubated with 2 nM CCL2 for 30 minutes (P = .002 for supernatant and P = .021 for cell lysates). (B) A total of 10⁸ erythrocytes from PRBC units were incubated with 2 nM CXCL1 or CXCL8. Increased soluble CXCL1 concentrations in 27-day-old RBCs compared with 12-day-old RBCs (P = .008); no difference in soluble CXCL8 concentrations (P = .999). (C) Duffy antigen expression on erythrocytes from banked blood (11 or 31 days old) compared with fresh erythrocytes isolated from healthy volunteers. (D) Storage time correlates with reduction in Duffy antigen expression on banked erythrocytes (P = .021).