Program: Oral and Poster Abstracts
Session: 401. Basic Science and Clinical Practice in Blood Transfusion: Poster III
Methods: Pre- and post-anti-RhD infusion samples were obtained from the hospital blood bank. Direct antiglobulin tests (DATs) were performed and assessed via flow cytometry on pre- and post-infusion samples. RBCs from pre- and post-infusion were also treated with Warm Autoantibody Removal Medium (WARM; ImmucorGamma, Norcross, GA), a sulphydryl/enzyme reagent based on the ZZAP method, in order to remove bound antibody. Post-WARM treated cells from pre- and post-anti-RhD infusion samples were then used to perform DATs. The presence of RhD antigen was assessed in pre- and post-infusion samples with in vitro anti-RhD, from the same lot number used to treat the patient, followed by anti-IgG and anti-complement as the secondary antibody. To account for the potential impact of bound antibody on antigen detection, antigen levels were also assessed after anti-RhD removal with the WARM method. Finally, in order to determine whether antigen loss was RhD specific, cellano (k) antigen detection was tested using anti-k antibody both pre- and post-WARM treatment.
Results: As predicted, the pre-anti-RhD infusion DAT was negative, while the post-anti-RhD injection DAT was positive (MFI 25). Post-WARM treatment, pre-and post-RhD infusion DATs showed minimal reactivity (MFI 3 and 5, respectively with background MFI of 2.7). Reduced RhD antigen levels were observed in post-anti-RhD infusion samples when compared to pre-infusion samples, while no complement could be detected in either pre- or post-anti-RhD infusion samples. The detection of antigen loss post-anti-RhD infusion was even more pronounced after RBCs were treated with WARM to remove previously bound anti-RhD antibody administered in vivo. In contrast, no difference in k antigen level could be detected pre- or post-anti-RhD infusion. As expected, post-WARM treatment, k antigen was no longer detectable pre- or post-anti-RhD infusion samples.
Conclusion: These results provide an example of antigen loss in the setting of anti-RhD administration. Moreover, the anti-RhD effect on the RhD-antigen appears to be antigen specific, as the RhD immune globulin did not modulate the k antigen on the same cell. Taken together, these results suggest that anti-RhD can induce the loss of detectable antigen independent of complement and may therefore influence the rate and magnitude of RBC clearance in settings of anti-RhD infusion, incompatible RBC transfusion and autoimmune hemolytic anemia.
Disclosures: No relevant conflicts of interest to declare.
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