Affinity and Epitope Profiling of Mouse Anti-CD40 Monoclonal Antibodies

The CD40-CD40L interaction plays a critical role in both humoral and cellular immune responses and interfering antibodies have been suggested as an effective approach for the treatment of lymphomas and autoimmune diseases. In this study we have profiled a panel of mouse antihuman CD40 monoclonal antibodies (MoAbs), regarding their CD40 binding affinity and epitope-specificity relative to the CD40L binding in relation to their cellular activating potential. Despite a rather similar domain-recognition profile, the MoAbs blocked the CD40L binding to a varying degree, with MoAb 5C3 being the poorest inhibitor. There was no correlation between affinity and cellular activation potential. In contrast, a correlation between the ability to block CD40L-binding and activation potential could be seen. We believe that this analysis of several mouse anti-CD40 antibodies can be used to develop strategies for producing new human anti-CD40 antibodies that can more effectively induce or block B-cell proliferation

Определение сроков годности экстракционных лекарственных средств корневищ с корнями синюхи голубой

РАСТЕНИЙ ЭКСТРАКТЫСИНЮХА ГОЛУБА

The CD40 Receptor - Target,Tool and Technology

CD40 is a cell surface receptor of pivotal importance that is expressed on several of the cells in the immune system. It is critical for many important events, such as T cell dependent B cell activation, isotype switching, somatic mutation and generation of B cell memory. The central role of CD40 in the immune system makes it an ideal target for antibody based immunotherapy. This led us to characterise a panel of monoclonal anti-CD40 antibodies. In PAPER I, we investigated their cellular activation potential and analysed to what extent this correlates with their affinity, epitope specificity and domain recognition profile. The antibody profiles we obtained in this first study may be valuable for understanding of the mechanisms that influence the therapeutic capacity of these antibodies. In fact, one of the antibodies that we investigated is currently in phase I/II trials. However, all of the antibodies that we characterised in PAPER I are of mouse origin, which probably limits their clinical efficiency, due to the human anti-mouse response that most patients develop against such antibodies. Therefore we selected a set of human anti-CD40 antibodies, which are described in PAPER II, from a recombinant antibody gene library. These antibodies display a wide variety of distinct properties, which may make them a valuable source when evaluating therapeutic candidates for in vivo trials. In PAPER III, we have used some of the anti-CD40 antibodies described in PAPER II to create an antibody library that was utilised to investigate antibody evolution in vitro. The results from this study showed that events, which resembles receptor revision, i.e. secondary rearrangements of antibody genes in the periphery, may provide an evolving antibody with competitive advantages during a selection process that is similar to the affinity maturation process in vivo. Our data reinforce the suggestion that receptor revision is an important complement to point mutations and insertions and deletions in the somatic hypermutation process that occur in germinal centres. It has been suggested that members of the TNFR family pre-associate in the membrane via one of the extracellular domains, the pre-ligand assembly domain (PLAD). Therefore, in PAPER IV, we investigated the functional role of the different domains of CD40, in a B cell model system. The results from this study showed that neither of the extracellular domains is essential for signal transduction and, furthermore, implies that conformational changes play no critical role for the CD40 signalling pathway. Based on the findings that all of the extracellular part of CD40 can be replaced with retained signalling capacity, we developed a novel selection method, named Selection of Protein Interactions by Receptor Engagement (SPIRE). In PAPER V, we demonstrated that this selection system can be used for clonal enrichment of cells that display a mock-CD40 receptor, used as prey, on the surface by interaction with a certain bait protein. Thus, SPIRE allows for clonal selection of interacting protein pairs in a mammalian environment. SPIRE may have several different applications such as identification of tumour antigens or for molecular evolution of complex proteins

A novel mammalian display system for the selection of protein-protein interactions by decoy receptor engagement

The emerging field of proteomics has created a need for new high-throughput methodologies for the analysis of gene products. An attractive approach is to develop systems that allow for clonal selection of interacting protein pairs from large molecular libraries. In this study, we have characterized a novel approach for identification and selection of protein-protein interactions, denoted SPIRE (selection of protein interactions by receptor engagement), which is based on a mammalian expression system. We have demonstrated proof of concept by creating a general plasma membrane bound decoy receptor, by displaying a protein or a peptide genetically fused to a trunctated version of the CD40 molecule. When this decoy receptor is engaged by a ligand to the displayed protein/peptide, the receptor expressing cell is rescued from apoptosis. To design a high-throughput system with a highly parallel capacity, we utilized the B cell line WEHI-231, as carrier of the decoy receptor. One specific peptide-displaying cell could be identified and amplified, based on a specific receptor engagement, in a background of 12 500 wild-type cells after four selections. This demonstrates that the approach may serve as a tool in post-genomic research for identifying protein-protein interactions, without prior knowledge of either component. Copyright (C) 2004 John Wiley Sons, Ltd

Identification of a strongly activating human anti-CD40 antibody that suppresses HIV-1 infection

We characterized the functional properties of a novel set of human anti-CD40 monoclonal antibodies originating from a human phage display library and identified an antibody that strongly activates cells via the CD40 receptor for potential use in HIV therapy. The anti-CD40 antibodies were converted from a single chain antibody fragment format (scFv) to an IgG format and produced in HEK293 cells, and the binding characteristics were evaluated. Next, their ability to (1) rescue a human B cell line from induced apoptosis, (2) stimulate B cell proliferation, and (3) block the CD40-CD40L interaction was determined. Finally, the most activating anti-CD40 antibody was tested for its ability to block HIV-1 infection in a monocyte-derived cell line.The different anti-CD40 antibodies, A24, B44, E30, F33, and A2-54, displayed a wide variety of binding and functional properties. In particular, B44 showed a very strong ability to activate normal human B cells and, in addition, did not block the CD40-CD40L interaction. This antibody was able to suppress HIV-1 infection in a human cell line (MonoMac 1) and may be a potential therapeutic candidate in HIV infection

Rationale and clinical development of CD40 agonistic antibodies for cancer immunotherapy

Introduction: CD40 signaling activates dendritic cells leading to improved T cell priming against tumor antigens. CD40 agonism expands the tumor-specific T cell repertoire and has the potential to increase the fraction of patients that respond to established immunotherapies. Areas covered: This article reviews current as well as emerging CD40 agonist therapies with a focus on antibody-based therapies, including next generation bispecific CD40 agonists. The scientific rationale for different design criteria, binding epitopes, and formats are discussed. Expert opinion: The ability of CD40 agonists to activate dendritic cells and enhance antigen cross-presentation to CD8+ T cells provides an opportunity to elevate response rates of cancer immunotherapies. While there are many challenges left to address, including optimal dose regimen, CD40 agonist profile, combination partners and indications, we are confident that CD40 agonists will play an important role in the challenging task of reprogramming the immune system to fight cancer