Accelerated removal of antibody-coated red blood cells from the circulation is accurately tracked by a biotin label

Abstract

Background: Safe, accurate methods to reliably measure circulating red blood cell (RBC) kinetics are critical tools to investigate pathophysiology and therapy of anemia, including hemolytic anemias. This study documents the ability of a method using biotin-labeled RBCs (BioRBCs) to measure RBC survival (RCS) shortened by coating with a highly purified monomeric immunoglobulin G antibody to D antigen.

Study design and methods: Autologous RBCs from 10 healthy D+ subjects were labeled with either biotin or (51) Cr (reference method), coated (opsonized) either lightly (n = 4) or heavily (n = 6) with anti-D, and transfused. RCS was determined for BioRBCs and for (51) Cr independently as assessed by three variables: 1) posttransfusion recovery at 24 hours (PTR(24) ) for short-term RCS; 2) time to 50% decrease of the label (T(50) ), and 3) mean potential life span (MPL) for long-term RCS.

Results: BioRBCs tracked both normal and shortened RCS accurately relative to (51) Cr. For lightly coated RBCs, mean PTR(24) , T(50) , and MPL results were not different between BioRBCs and (51) Cr. For heavily coated RBCs, both short-term and long-term RCS were shortened by approximately 17 and 50%, respectively. Mean PTR(24) by BioRBCs (84 ± 18%) was not different from (51) Cr (81 ± 10%); mean T(50) by BioRBCs (23 ± 17 days) was not different from (51) Cr (22 ± 18 days).

Conclusion: RCS shortened by coating with anti-D can be accurately measured by BioRBCs. We speculate that BioRBCs will be useful for studying RCS in conditions involving accelerated removal of RBCs including allo- and autoimmune hemolytic anemias.

© 2011 American Association of Blood Banks.

Figures

Fig. 1

Survival curves of Subjects 1 to 4 for (●) 51Cr- and (엯) biotin-labeled RBCs lightly coated with anti-D before transfusion. 51Cr whole blood concentration was corrected for both elution and 51Cr decay. Values are expressed as percentage of Day 0 (10 min) value.

Fig. 2

Survival curves for subjects 5-10 for (●) 51Cr- and (엯) biotin-labeled RBCs heavily coated with anti-D before transfusion. 51Cr: blood concentration of RBC-associated 51Cr as described in the legend to Fig. 1.