[PMC free article] [PubMed] [Google Scholar] 4. of anti-RhD immunoglobulin (Ig)G (WinRho) and subsequently experienced a hemolytic reaction. In the blood bank, a postinfusion direct anti-globulin test (DAT) was positive (IgG, 3+; C3, 0). Because a preinfusion sample was available, this reaction provided an opportunity to assess RhD antigen expression before and after anti-RhD infusion. To provide a more quantitative evaluation of antibody and antigen levels before and after anti-RhD infusion, DATs were assessed by flow cytometry. As predicted, the preCanti-RhD infusion DAT was negative, and the postCanti-RhD DAT was positive (Fig. 1A). To evaluate RhD antigen levels, preinfusion and postinfusion samples were incubated in vitro with anti-RhD (with the same lot number used to treat the patient), followed by anti-IgG and anticomplement. Reduced levels of detectable RhD Regorafenib monohydrate antigen were observed in the postCanti-RhD infusion sample compared with the preinfusion sample (Fig. 1B); however, no complement could be detected on the surface of RBCs either before or after anti-RhD infusion (data not shown). Open in a separate window Fig. 1. Anti-RhD induces loss of the RhD antigen. (A) DAT results are illustrated before and after anti-RhD exposure (black, patient serum; gray, negative control). Regorafenib monohydrate (B) RhD antigen levels are illustrated before (gray) and after (black) anti-RhD exposure. (C) DAT results are illustrated before and after anti-RhD exposure (black, patient serum; gray, negative control) following EGA treatment. (D) RhD antigen levels are illustrated before (gray) and after (black) anti-RhD exposure following EGA treatment. (E,F) Cellano (k antigen) levels are illustrated before (gray) and after (black) anti-RhD exposure in the (E) absence or (F) presence of EGA treatment. Given the potential confounding effect of antibody already bound in vivo on the detection of the RhD antigen postCanti-RhD infusion, we removed bound anti-RhD antibody using ethylenediaminetetraacetate glycine acid (EGA) (ImmucorGamma), which dissociates bound IgG from the RBC surface. After EGA treatment, DATs before and after anti-RhD infusion revealed minimal reactivity (Fig. 1C). Using this approach, antigen loss after anti-RhD infusion was still apparent when directly comparing RBCs after and before anti-RhD infusion (Fig. 1D). Finally, to determine whether reduction in the level of detectable antigen was specific to the RhD antigen, we evaluated cellano (k) antigen levels before and after anti-RhD exposure. Unlike the observed alterations of RhD, no difference in k antigen was detected before or after anti-RhD infusion (Fig. 1E). Because EGA is known to disrupt the k antigen, no k antigen was detected post-EGA treatment from preCanti-RhD or postCanti-RhD infusion samples (Fig. 1F). Because most autoimmune hemolytic anemia or hemolytic transfusion reactions are not anticipated, it is difficult to examine potential changes in target antigen before and after antibody engagement. However, this case provided a unique opportunity to examine the impact of antibody engagement on a RBC antigen using defined anti-RhD reagents used not only to treat the patient but Regorafenib monohydrate also to define changes in RhD antigen levels. Although it is certainly possible that the apparent impact of anti-RhD on RhD antigen levels may reflect undetectable masking by anti-RhD Fab fragments, the ability of EGA treatment to largely eliminate the binding of intact IgG strongly suggests that potential Fab fragments would be similarly removed. Furthermore, because anti-RhD antibodies do not typically fix complement, examination of RBCs before and after Mouse monoclonal to CD147.TBM6 monoclonal reacts with basigin or neurothelin, a 50-60 kDa transmembrane glycoprotein, broadly expressed on cells of hematopoietic and non-hematopoietic origin. Neutrothelin is a blood-brain barrier-specific molecule. CD147 play a role in embryonal blood barrier development and a role in integrin-mediated adhesion in brain endothelia anti-RhD exposure provides an opportunity to determine the impact of antibody engagement in the absence of complement fixation. Our case demonstrates that, in the clinical setting, anti-RhD antibodies can induce Regorafenib monohydrate specific alterations in the levels of detectable RhD antigen, consistent with previous studies suggesting that similar alterations can occur in the setting of passive antibody administration.3 Although antibody engagement can result in complete.
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