Monoclonal Antibodies in Immunodiagnosis and Immunotherapy最新文献

CC chemokine receptor type-2 (CCR2) belongs to the G protein-coupled receptors superfamily, and is localized on cell surface of tumor cells and some immune cells, including monocytes and macrophages. CCR2 is a receptor for monocyte chemoattractant protein-1/C-C motif chemokine 2, and is involved in the progression of various diseases such as cancers. Therefore, the development of CCR2-targeted monoclonal antibody (mAb) is desired. Its characterization, including epitope of mAb, is very important for antibody applications. In this study, we investigated the critical epitope of K036C2, which is a commercially available anti-human CCR2 (hCCR2) mAb. We conducted enzyme-linked immunosorbent assay (ELISA) using three N-terminal peptides of hCCR2 and demonstrated that K036C2 recognizes 11-29 and 21-39 amino acids of hCCR2. We further performed ELISA using 20 peptides, which include alanine substitution of hCCR2. K036C2 lost the reaction to the alanine-substituted peptides of D25A, Y26A, D27A, G29A, and A30G. These results indicate that the critical binding epitope of K036C2 includes Asp25, Tyr26, Asp27, Gly29, and Ala30 of hCCR2.

Monoclonal antibodies (MAbs) against epizootic hemorrhagic disease virus (EHDV) were produced by immunizing BALB/c mice with rec-VP7-EHDV2; 66 clones producing MAbs able to recognize the VP7-EHDV with a strong reaction were obtained and tested in indirect enzyme-linked immunosorbent assay (i-ELISA) against the whole epizootic hemorrhagic disease (EHD) virus serotype 2; potential cross-reactions with related orbiviruses, as Bluetongue virus (BTV) and African horse sickness virus (AHSV), were investigated as well by i-ELISA, Western blot, and immunofluorescence. Fifty-three MAbs were specific for EHDV (VP7 recombinant protein and whole virus) and 13 reacted also with the VP7 of BTV. None of the MAbs reacted with AHSV. MAbs specific for EHDV were further characterized in a competitive ELISA (c-ELISA): 20 among them were found useful to develop a c-ELISA for the detection of antibodies against EHDV in bovine sera. The availability of this extensive set of MAbs provides the opportunity to develop a c-ELISA for the serological diagnosis of EHDV and to tune new methods for the isolation and identification of the virus in biological samples and cell cultures. The experimentation protocol was approved by the Italian Ministry of Health (number 639/2018-PR, Resp. to Prot. BDF16.13#295833199#).

Monoclonal antibodies (mAbs) against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes COVID-19, are the important tools both for the diagnosis and therapeutics of this infectious disease. The high-performance antibody against spike protein of SARS-CoV-2 is expected to inhibit the binding of viruses to their receptors on the surface of their target cells. In this study, we propose the novel screening method for mAbs against the pathogenic infectious virus using exosome. By this method, the exosome that artificially expresses SARS-CoV-2 spike protein was purified and used as a virus-like vesicle, which could bind to the viral receptor, angiotensin-converting enzyme 2 (ACE2). As a result, seven mAbs that could bind to the spike protein were obtained and six of these clones could strongly inhibit the binding to ACE2 of both the protein corresponding to the receptor binding domain (RBD) and the exosome expressing the spike protein. Interestingly, some of these antibodies seemed to share their epitopes in RBD, suggesting that highly antigenic sites exist in the spike protein. In view of the neutralizing activities on infection, five clones of these antibodies could inhibit the internalization of vesicular stomatitis virus-based pseudo viruses expressing various types of spike proteins derived from SARS-CoV-2 variants. In addition, these antibodies inhibited the infection of SARS-CoV-2 to cultured mammalian cells. These antibodies are expected to be utilized for both diagnosis and therapeutics of COVID-19.

Blockade of the PD-L1/PD-1 pathway has proven to be a broadly effective cancer immunotherapy. FDA-approved therapeutic monoclonal antibodies (mAbs) targeting the pathway have high affinity, blocking capacity, and low antibody effector activity. A number of rat antimouse mAbs have been used to model cancer immunotherapy in mouse models. We set forth the amino acid sequences of mAbs specific for mouse PD-1 (29F.1A12) and PD-L1 (10F.9G2) and compare their avidities, blocking capacities, biological activities, and epitope recognition with other commonly used mAbs. Further manipulation of these sequences should facilitate better modeling of immunotherapy in mouse models and the generation of novel agents.

Podoplanin (PDPN) is a marker of lung type I alveolar cells, kidney podocytes, and lymphatic endothelial cells. The overexpression of PDPN contributes to the malignant progression of tumors. Therefore, the development of anti-PDPN monoclonal antibodies (mAbs) to animals is essential to evaluate the pathogenesis and cellular functions. Using peptide immunization, we previously developed an anti-elephant PDPN (elePDPN) mAb, PMab-295, which is useful for flow cytometry, Western blotting, and immunohistochemistry. In this study, we determined the critical epitope of PMab-295 by enzyme-linked immunosorbent assay (ELISA). We performed ELISA with the alanine-substituted peptides of elePDPN extracellular domain (amino acids 38-51), and found that PMab-295 did not recognize the alanine-substituted peptides of M41A, P44A, and E47A. Furthermore, these peptides could not inhibit the recognition of PMab-295 to elePDPN-expressing cells by flow cytometry and immunohistochemistry. The results indicate that the binding epitope of PMab-295 includes Met41, Pro44, and Glu47 of elePDPN.

Monoclonal antibody (mAb) therapy has emerged as one of the mainstay treatment options for SARS-CoV-2. To improve speed of delivery and decrease bedside nursing needs, subcutaneous (SC) delivery of mAbs has been explored as an alternative to standard intravenous (IV) administration. To date, data regarding the effectiveness of SC compared with IV mAb are lacking. This retrospective cohort analysis conducted between April 2021 and August 2021 compared hospitalization rates among patients receiving IV versus SC administration of casirivimab/imdevimab (Regen-COV) at a single institution in Arkansas. Casirivimab/imdevimab was a promising mAb therapy utilized during the height of the Delta variant surge of the SARS-CoV-2 pandemic. Before resistance developed by the Omicron variant, casirivimab/imdevimab was utilized for outpatient treatment of SARS-CoV-2 patients at risk of deterioration. Primary outcomes of this investigation were the 30-day post-treatment rate of hospitalization and intensive care unit (ICU) care during hospitalization. There was no increased risk of hospitalization or ICU care with SC administration compared with IV administration. As SARS-CoV-2 continues to mutate into variants such as Omicron and develop resistance to existing mAbs, these preliminary findings of noninferiority of SC versus IV warrant ongoing investigation into SC administration of other mAbs.

Podoplanin (PDPN) is an essential marker of lung type I alveolar cells, kidney podocytes, and lymphatic endothelial cells. Monoclonal antibodies (mAbs) that can specifically recognize PDPN in immunohistochemistry are important to analyze the development of tissues and the pathogenesis of diseases, including cancers. We have developed anti-PDPN mAbs against many animal species; however, mAbs that can recognize elephant-derived membrane proteins and distinguish the specific cell types in immunohistochemistry are limited. In this study, a novel anti-elephant PDPN (elePDPN) mAb, PMab-295 (IgG₁, kappa), was established using the peptide immunization method. PMab-295 recognized both elePDPN-overexpressed Chinese hamster ovary (CHO)-K1 cells and endogenous elePDPN-expressed LACF-NaNaI cells by flow cytometry and western blotting. Kinetic analyses using flow cytometry showed that the K_D of PMab-295 for CHO/elePDPN was 1.5 × 10^-8 M. Furthermore, PMab-295 detected elePDPN-expressing cells using immunohistochemistry. These results showed the usefulness of PMab-295 to investigate the molecular function of elePDPN and the pathogenesis of diseases.

C-C chemokine receptor 4 (CCR4) is one of G protein-coupled receptors, and interacts with chemokines, CCL17 and CCL22. CCR4 is expressed on T cells such as helper T type 2 cells, regulatory T cells, and interleukin 17-producing T helper cells. CCR4 is associated with T cells trafficking into the tumor microenvironment, and is associated with tumor progression or metastasis. Therefore, CCR4 may be a potential therapeutic option for T cell malignancies. C₄Mab-1 is a novel anti-mouse CCR4 (mCCR4) monoclonal antibody produced by mCCR4 N-terminal peptide immunization. C₄Mab-1 is useful for flow cytometric analysis. In this study, we conducted the epitope mapping of C₄Mab-1 using enzyme-linked immunosorbent assay (ELISA) and peptide blocking assay. The result of ELISA indicated that Thr7, Asp8, and Gln11 of mCCR4 are the critical amino acids for the C₄Mab-1 binding. Furthermore, peptide blocking assay by flow cytometry showed that Thr7, Asp8, and Gln11 of mCCR4 are essential for C₄Mab-1 binding to mCCR4-overexpressed Chinese hamster ovary-K1 (CHO/mCCR4) cells, and Val6, Thr9, and Thr10 are involved in the C₄Mab-1 binding to CHO/mCCR4 cells. These results indicate that the critical binding epitope of C₄Mab-1 includes Thr7, Asp8, and Gln11 of mCCR4.

The CC chemokine receptor type-2 (CCR2) is one of the members of the G protein-coupled receptor superfamily, which are expressed on the cell surface of immune and tumor cells. CCR2 binds to the C-C motif chemokine ligand 2 (CCL2)/monocyte chemoattractant protein-1 (MCP-1), which is produced by various cells, including tumor and immune-related cells. Therefore, the development of sensitive monoclonal antibodies (mAbs) for CCR2 has been desired for treatment and diagnosis. In this study, we established a specific antihuman CCR2 (hCCR2) mAb, C₂Mab-9 (mouse IgG₁, kappa), using the synthetic peptide immunization method. Flow cytometric and immunocytochemical results showed that C₂Mab-9 reacted with hCCR2-expressing U937 (human histiocytic lymphoma) and natural killer cells. Furthermore, C₂Mab-9 showed the moderate binding affinity for both cells. Conclusively, C₂Mab-9 can be a useful tool for analyzing hCCR2-related biological responses.