• B-RBCs = biotin-labeled (biotinylated) RBCs;
  • RBC(s) = red cell(s);
  • sulfo-NHS = sulfo-N-hydroxysuccinimide

BACKGROUND: Biotin-labeled (biotinylated) red cells (B-RBCs) offer a technique by which to study RBC volume and circulating kinetics without in vivo radiation. The immunogenicity of B-RBCs is undefined.

STUDY DESIGN AND METHODS: To determine if biotinylation renders RBCs immunogenic, autologous B-RBCs were transfused to 20 healthy subjects, and plasma samples were obtained before transfusion and serially for up to 6 months after transfusion. These serial samples, plus plasma from 20 normal control subjects not given B-RBCs, were screened for antibodies to B-RBCs by use of an antiglobulin technique against aliquots of group O RBCs from a single donor—one aliquot biotinylated and one aliquot not biotinylated (i.e., test and control RBCs). Posttransfusion recovery and survival of B-RBCs were also determined.

RESULTS: Plasma from none of 20 normal nontransfused subjects reacted with B-RBCs. Similarly, none of the 20 subjects given autologous B-RBC transfusions exhibited antibodies before transfusion. However, 3 of the 20 subjects transiently produced antibodies to B-RBCs after transfusion. Antibodies disappeared within 6 months in 2 of these 3 subjects and within 12 months in the third. Antibody reactivity was not reduced by dithiothreitol, but in 2 of the 3 subjects, B-RBC antibodies were neutralized by incubation with biotin solution. Circulating RBC kinetics were not altered in the 3 subjects with antibody. The significance of these observations is unclear, because antibodies were just beginning to emerge during the studies.

CONCLUSIONS: Biotinylation does not render RBCs reactive with normal human plasma (i.e., presumably does not evoke neoantigens). Transfused B-RBCs occasionally provoke IgG antibodies in healthy subjects. Because the biologic effects of B-RBC antibodies currently are unknown, testing for them is recommended when multiple B-RBC transfusions are given to study RBC volume or circulating kinetics.