A novel acridine flow cytometry marker to track post-transfusion amustaline/glutathione pathogen-reduced red blood cell survival in sickle cell disease patients.

BACKGROUND

Measurement of transfused red blood cell (RBC) survival is relevant to the effective management of sickle cell disease (SCD). Following amustaline/glutathione pathogen-reduced (PR) RBC transfusion, small quantities of PR-RBC surface-bound acridine are detectable by flow cytometry. Concurrent biotin labeling was used to validate the acridine marker and track transfused PR-RBCs in SCD.

METHODS

SCD patients (n = 6) on chronic transfusion therapy received three aliquots of different (2 μg/mL, 6 μg/mL, and 18 μg/mL) biotin-dose labeled RBCs during one transfusion episode. Aliquots were from one unit labeled before (Pre-PR) and after PR treatment (PR-RBC) and from a conventional RBC unit. The full RBC units (PR and conventional) were transfused, followed by the labeled aliquots from those units. Serial flow cytometry analyses for acridine- and biotin-labeled RBCs were performed on 10 occasions over 16 weeks. Acridine surface density was quantitated using calibrated beads.

RESULTS

Mean acridine surface density was 5062 molecules/PR-RBC at 1-4 h post-transfusion and declined 84.5% within 7 days, remaining detectable (180 molecules/PR-RBC) at 16 weeks. The biotin-labeled PR-RBC aliquots (initial enrichment 0.6%-1.4%) demonstrated near-identical survival kinetics as the entire acridine-labeled PR-RBC units (initial enrichment 7.5%-13.7%). Pre-PR, PR, and Conventional RBCs revealed non-linear RBC survival kinetics, with similar 24-h post-transfusion recoveries (PTR) and half-lives (T), but PR-RBC mean predicted lifespan (mean [SD] 104.4 [4.7] days) was decreased by 9.3% (Pre-PR-RBCs 115.1 [7.2] days, p = 0.006).

CONCLUSIONS

Survival of amustaline/glutathione PR-RBCs can be tracked in vivo by flow cytometry for RBC surface acridine with similar sensitivity as biotin, without additional processing or radiolabeling.