Recombinant H22(scFv) blocks CD64 and prevents the capture of anti-TNF monoclonal antibody

Hristodorov, Dmitrij; Mladenov, Radoslav; Brehm, Hannes; Fischer, Rainer; Barth, Stefan; Thepen, Theo

doi:10.4161/mabs.32182

Cited by 5 publications

(6 citation statements)

References 31 publications

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“…Furthermore, we have been unable to recapitulate the inhibitory signaling through FcγRI in THP‐1 cells that is robustly induced in primary human monocytes and macrophages in response to immune complexes (G. Boekhoudt, D. Haddad, and J. Swisher, unpublished data). On the basis of this work, it was thought that blockade of FcγRI with antibody fragments might potentiate the efficacy of TNF antagonists . While the fragments prevented binding of therapeutic TNF antagonist antibodies to FcRs, there was little data to suggest that it would be therapeutically useful in vivo .…”

Section: Fcγri and Tnf Antagonistsmentioning

confidence: 99%

The many faces of FcγRI: implications for therapeutic antibody function

Swisher

Feldman

2015

Immunological Reviews

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Fcγ receptor I (FcγRI or CD64) is the sole human Fc receptor with high affinity for monovalent IgG. While it contains an immunoreceptor tyrosine-based activation motif in its cytoplasmic domain, binding of FcγRI can result in a complex array of activating and inhibitory outcomes. For instance, binding of monomeric IgG provides a low-intensity tonic signal through FcγRI that is necessary for full interferon γ receptor signaling in the same cell. Interaction of FcγRI with larger high-avidity complexes can result in phagocytosis, the generation of reactive oxygen species, as well as the synthesis and release of inflammatory cytokines. However, numerous reports also document potent anti-inflammatory effects brought about by FcγRI engagement with immune complexes such as the inhibition of IFNγ and TLR4 signaling, and secretion of interleukin-10. This has led to conflicting hypotheses regarding the function of FcγRI, especially with regard to its role in the efficacy of several therapeutic monoclonal antibodies. While many of these issues are still unclear, continued characterization of the regulation and context dependence of FcγRI function, as well as the molecular mechanisms responsible for these various outcomes, will improve our understanding of FcγRI biology as well as the therapeutic strategies designed to harness or constrain its actions.

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Section: Fcγri and Tnf Antagonistsmentioning

confidence: 99%

The many faces of FcγRI: implications for therapeutic antibody function

Swisher

Feldman

2015

Immunological Reviews

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“…Interestingly, we observed upregulation of cell‐surface CD89 not only following treatment with TNFα but also when CD64 was blocked with H22(scFv). Since H22(scFv) does not affect the expression of TNFα, our data show that CD89 can be induced in a TNFα‐independent manner. This is particularly interesting because there have been no previous reports showing interactions between CD89 and CD64 in the myeloid lineage, although they share the FcRγ chain .…”

Section: Discussionmentioning

confidence: 72%

“…S1). Potential interactions between CD64 and CD89 were investigated by treating the cells with the CD64‐specific antibody fragment H22(scFv), which selectively binds to and blocks CD64 without activating it . This treatment induced the expression of CD89 on the surface of all cell lines except U937, where the abundance remained at fewer than 500 receptors per cell regardless of the stimulus.…”

Section: Resultsmentioning

confidence: 99%

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The Fc‐alpha receptor is a new target antigen for immunotherapy of myeloid leukemia

Mladenov

Hristodorov

Cremer

et al. 2015

Intl Journal of Cancer

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Antibody-based immunotherapy of leukemia requires the targeting of specific antigens on the surface of blasts. The Fc gamma receptor (CD64) has been investigated in detail, and CD64-targeting immunotherapy has shown promising efficacy in the targeted ablation of acute myeloid leukemia (AML), acute myelomonocytic leukemia (AMML) and chronic myeloid leukemia cells (CML). Here we investigate for the first time the potential of FcaRI (CD89) as a new target antigen expressed by different myeloid leukemic cell populations. For specific targeting and killing, we generated a recombinant fusion protein comprising an anti-human CD89 single-chain Fragment variable and the well-characterized truncated version of the potent Pseudomonas aeruginosa exotoxin A (ETA'). Our novel therapeutic approach achieved in vitro EC 50 values in range 0.2-3 nM depending on the applied stimuli, that is, interferon gamma or tumor necrosis factor alpha. We also observed a dose-dependent apoptosis-mediated cytotoxicity, which resulted in the elimination of up to 90% of the target cells within 72 hr. These findings were also confirmed ex vivo using leukemic primary cells from peripheral blood samples of three previously untreated patients. We conclude that CD89-specific targeting of leukemia cell lines can be achieved in vitro and that the efficient elimination of leukemic primary cells supports the potential of CD89-ETA' as a potent, novel immunotherapeutic agent.Under normal physiological conditions, the Fc-alpha receptor (FcaR, CD89) is present on monocytes, macrophages, neutrophils and eosinophils. Its biological function is to interact with IgA-opsonized targets, triggering several immunological defense processes, e.g. phagocytosis, antibody-dependent cellmediated cytotoxicity and the stimulation of inflammatory mediators. 1 In many human tissues, most of the CD89 1 cells are neutrophils and monocytes/macrophages. Furthermore, although monocytes in the blood express relatively high levels of CD89, most tissue macrophages (particularly those located in the gut lamina propria) tend not to express CD89 on the surface, with a parallel downregulation of CD14. 2 This suggests that the abundance of CD89 depends on the differentiation stage of myeloid cells. The biological relevance of CD89 downregulation during the maturation of myeloid precursor cells is unknown.On the other hand, the presence of anomalous numbers of myeloid cells in the blood is indicative of several myelogenous hematological malignancies, with AML and CML being the most common. 3 The different forms of myeloid leukemia have been categorized using the French-American-British (FAB) system divided into eight subtypes (M0-M7). The World Health Organisation (WHO) uses expanded criteria. 4 A standard panel of markers is used for detailed diagnosis and classification, including Fc gamma receptor (FcgRI) (CD64) which is present on AML subtypes M0-M5 in varying degrees. 5 Thus far, there is no evidence that other Fc receptors can be used as diagnostic antigens or therapeutic targets in A...

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“…For blocking experiments, arrays containing 10 μg of neutralizing antibodies against human CD32 (IV.3, STEMCELL Technologies) or CD64 (10.1; BioLegend) or isotype control antibodies combined with either DENV-3 immune or flavivirus-naive sera at 1:40 dilution were formulated. The concentration of neutralizing antibodies was twice the neutralization dose required to saturate surface expression of CD32 and CD64 molecules (36,61) multiplied by a factor of 2.3 to compensate for dilution following dispersal within skin.…”

Section: Methodsmentioning

confidence: 99%