Preanalytic depletion of medicinal anti-CD38 antibody from patient plasma for immunohematology testing

Pretreatment with Daudi cells eliminates anti-CD47 monoclonal antibody interference in immunohematology testing

BACKGROUND

Anti-CD47 monoclonal antibodies have increasing clinical applications in the treatment of cancer. However, anti-CD47 monoclonal antibodies interfere with immunohematology testing in patients who require blood transfusion. As the current approaches to removing any interferences have technical problems, new methods need to be developed to resolve anti-CD47 interference in immunohematology testing.

MATERIALS AND METHODS

We evaluated the Daudi cell line for the adsorption of free anti-CD47 monoclonal antibodies from patients' plasma to facilitate immunohematology testing in patients treated with anti-CD47 monoclonal antibody. CD47 expression was identified on the Daudi cells using flow cytometry and confocal microscopy. Next, we tested the ability of intact Daudi cells mixed with simulating plasma and clinical samples to achieve efficient removal of interfering anti-CD47 monoclonal antibodies. The indirect antiglobulin test was used to verify whether interference from anti-CD47 monoclonal antibodies in plasma was eliminated and whether the detection of other irregular antibodies was affected. The effect of eliminating interference was also investigated in relation to the time that the Daudi cells were stored after having been fixed with paraformaldehyde.

RESULTS

CD47 expression was higher on Daudi cells than on red blood cells. Analysis of the indirect antiglobulin test results revealed that anti-CD47 monoclonal antibody-treated patients' plasma absorbed by Daudi cells for 15 min at 37°C could completely prevent the interference of anti-CD47 monoclonal antibodies in immunohematology testing while the detection of the tested antibodies, including anti-D and anti-K, was unaffected.

DISCUSSION

By decreasing the incubation time, we discovered that interferences in samples with agglutination strengths below 2+ could be eliminated after incubation for 5 min. Of importance, Daudi cells can be preserved with 4% paraformaldehyde for 14 days as short-term storage reagents. This is the first study in which Daudi cells were used to effectively resolve the interference of anti-CD47 monoclonal antibodies in pretransfusion tests.

Mitigation of therapeutic anti-CD38 antibody interference with fab fragments: How well does it perform?

BACKGROUND

Administration of anti-CD38 antibodies is a state-of-the-art therapy for patients diagnosed with multiple myeloma (MM). However, this treatment frequently leads to pan-agglutination of red blood cells (RBCs) in patients' serological testing making accurate blood typing and timely transfusion of compatible blood a challenging effort. The antigen masking indirect antiglobulin test (AMIAT) is an approach to address this diagnostic challenge.

STUDY DESIGN AND METHODS

A new reagent, called DaraEx plus, uses anti-CD38 Fab fragments to mitigate the anti-CD38 antibody interference in serological assays by masking CD38 on the cell surface. Its performance is extensively examined with commercial sera as well as with patient samples, and compared to the current standard method using dithiothreitol (DTT), which denatures the CD38 antigens on test panel erythrocytes.

RESULTS

In the Bio-Rad ID System, DaraEx plus effectively mitigated the interference caused by anti-CD38 antibodies in 86% of patient samples tested while DTT was successful in only 68%. Moreover, there was no negative influence on DTT-sensitive blood group systems such as KEL upon DaraEx plus treatment. The agglutination reactions of all tested anti-CD38 antibodies (Daratumumab, Felzartamab, and Isatuximab) were inhibited by DaraEx plus. The treatment was successful only if DaraEx plus was added to the test cells before the sample. Some of the other gel card systems tested showed background reactions with DaraEx plus-treated cells.

CONCLUSION

DaraEx plus treatment is straightforward and quick to perform. In the Bio-Rad ID System, it is superior to DTT treatment in the prevention of anti-CD38 antibody interference.

Efficient neutralization of daratumumab in pretransfusion samples using a novel recombinant monoclonal anti-idiotype antibody

BACKGROUND

Anti-CD38 antibodies such as daratumumab (DARA) are critical therapies for multiple myeloma and other diseases. Unfortunately, anti-CD38 antibodies cause panreactivity in indirect antiglobulin tests (IATs), complicating blood compatibility testing. The anti-CD38 interference is most often mitigated by treating reagent red blood cells (RBCs) with dithiothreitol (DTT). However, when using the DTT method, not all RBC antibody specificities can be detected (e.g., anti-K), and the DTT method is impractical for some transfusion services. We evaluated the ability of a new anti-idiotype antibody to neutralize DARA in vitro and eliminate the anti-CD38 interference.

STUDY DESIGN AND METHODS

A recombinant monoclonal rabbit anti-DARA idiotype antibody ("anti-DARA") was generated. The ratio of anti-DARA required to neutralize DARA in spiked samples was evaluated in IATs performed in gel. IATs performed in tube were used to demonstrate that anti-DARA allows alloantibody detection in the presence of DARA. Plasma samples from 29 patients receiving DARA were treated with a fixed quantity of anti-DARA (120 μg) before performing antibody detection tests (screens) in tube.

RESULTS

Anti-DARA used at or above a 1:1 ratio with DARA eliminated the DARA interference with IATs. Anti-DARA allowed detection of both alloanti-E and alloanti-K in the presence of DARA. In 27/29 (93.1%) clinical samples, 120 μg anti-DARA was sufficient to neutralize the DARA in 100 μl patient plasma.

DISCUSSION

An anti-DARA:DARA ratio as low as 1:1 is sufficient to neutralize DARA in solution. A fixed amount of anti-DARA eliminates the anti-CD38 interference in most patient samples.

Current advances in transfusion medicine 2021: A critical review of selected topics by the AABB Clinical Transfusion Medicine Committee

BACKGROUND

Each year the AABB Clinical Transfusion Medicine Committee (CTMC) procures a synopsis highlighting new, important, and clinically relevant studies in the field of transfusion medicine (TM). This has been made available as a publication in Transfusion since 2018.

METHODS

CTMC members reviewed and identified original manuscripts covering TM-related topics published electronically (ahead-of-print) or in print from December 2020 to December 2021. Selection of publications was discussed at committee meetings and chosen based on perceived relevance and originality. Next, committee members worked in pairs to create a synopsis of each topic, which was then reviewed by additional committee members. The first and senior authors assembled the final manuscript. Although this synopsis is extensive, it is not exhaustive, and some articles may have been excluded or missed.

RESULTS

The following topics are included: blood products; convalescent plasma; donor collections and testing; hemoglobinopathies; immunohematology and genomics; hemostasis; patient blood management; pediatrics; therapeutic apheresis; and cell therapy.

CONCLUSIONS

This synopsis highlights and summarizes recent key developments in TM and may be useful for educational purposes.