scholarly journals The structural features that distinguish PD-L2 from PD-L1 emerged in placental mammals

2019 ◽  
Vol 295 (14) ◽  
pp. 4372-4380 ◽  
Author(s):  
Elliot A. Philips ◽  
Antonio Garcia-España ◽  
Anna S. Tocheva ◽  
Ian M. Ahearn ◽  
Kieran R. Adam ◽  
...  
Keyword(s):  
Adaptive Immune System ◽  
Structural Features ◽  
Inhibitory Receptor ◽  
Programmed Death Ligand 1 ◽  
Lower Affinity ◽  
Adaptive Immune ◽  
Programmed Death ◽  
D Region ◽  
Antigen Presenting ◽  
Cell Death Protein

Programmed cell death protein 1 (PD-1) is an inhibitory receptor on T lymphocytes that is critical for modulating adaptive immunity. As such, it has been successfully exploited for cancer immunotherapy. Programmed death ligand 1 (PD-L1) and PD-L2 are ligands for PD-1; the former is ubiquitously expressed in inflamed tissues, whereas the latter is restricted to antigen-presenting cells. PD-L2 binds to PD-1 with 3-fold stronger affinity compared with PD-L1. To date, this affinity discrepancy has been attributed to a tryptophan (W110PD-L2) that is unique to PD-L2 and has been assumed to fit snuggly into a pocket on the PD-1 surface. Contrary to this model, using surface plasmon resonance to monitor real-time binding of recombinantly-expressed and -purified proteins, we found that W110PD-L2 acts as an “elbow” that helps shorten PD-L2 engagement with PD-1 and therefore lower affinity. Furthermore, we identified a “latch” between the C and D β-strands of the binding face as the source of the PD-L2 affinity advantage. We show that the 3-fold affinity advantage of PD-L2 is the consequence of these two opposing features, the W110PD-L2 “elbow” and a C–D region “latch.” Interestingly, using phylogenetic analysis, we found that these features evolved simultaneously upon the emergence of placental mammals, suggesting that PD-L2–affinity tuning was part of the alterations to the adaptive immune system required for placental gestation.

Cellular side of acquired immunity (B cells)

2013 ◽  
pp. 371-378
Author(s):  
Thomas Dörner ◽  
Peter E. Lipsky
Keyword(s):  
B Cells ◽  
B Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Plasma Cells ◽  
Adaptive Immune System ◽  
Adaptive Immune ◽  
B Cell Homeostasis ◽  
Anti Cd20 ◽  
Antigen Presenting

B cells have gained interest in rheumatoid arthritis (RA) beyond being the precursors of antibody-producing plasma cells since they are also a broader component of the adaptive immune system. They are capable of functioning as antigen-presenting cells for T-cell activation and can produce an array of cytokines. Disturbances of peripheral B-cell homeostasis together with the formation of ectopic lymphoid neogenesis within the inflamed synovium appears to be a characteristic of patients with RA. Enhanced generation of memory B cells and autoreactive plasma cells producing IgM-RF and ACPA-IgG antibodies together with formation of immune complexes contribute to the maintenance of RA, whereas treatment with B-cell-directed anti-CD20 and CLTA4-Ig therapy provides clinical benefit.

scholarly journals Daratumumab prevents programmed death ligand‐1 expression on antigen‐presenting cells in de novo multiple myeloma

2020 ◽  
Vol 9 (6) ◽  
pp. 2077-2084 ◽  
Author(s):  
Nicolas Stocker ◽  
Béatrice Gaugler ◽  
Laure Ricard ◽  
Frédéric Vassoigne ◽  
Zora Marjanovic ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
De Novo ◽  
Antigen Presenting Cells ◽  
Programmed Death Ligand 1 ◽  
Programmed Death ◽  
Antigen Presenting

Antigen-Specific Transfer of Functional Programmed Death Ligand 1 From Antigen Presenting Cells Onto Human CD8+ T Cells Via Trogocytosis

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 584-584
Author(s):  
Regina Gary ◽  
Simon Voelkl ◽  
Ralf Palmisano ◽  
Andreas Mackensen
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
T Cell Responses ◽  
Antigen Presenting Cells ◽  
Programmed Death Ligand 1 ◽  
Cell Responses ◽  
Surface Molecules ◽  
Programmed Death ◽  
Antigen Presenting

Abstract Abstract 584 Specific T-cell responses are initiated by T-cell receptor (TCR) recognition of peptide-MHC-complexes on antigen presenting cells (APCs). Upon specific interaction of T cells with APCs T cells capture membrane fragments and surface molecules of APCs in a process termed trogocytosis. Exchange of membrane molecules/antigens between immune cells has been observed for a long time, but the mechanisms and functional consequences of these transfers remain unclear. Here, we demonstrate that human antigen-specific CD8+ T cells do acquire the co-inhibitory molecule programmed death ligand 1 (PD-L1) from mature monocyte-derived dendritic cells (mDC) and tumor cells in an antigen-specific manner. The kinetics of PD-L1 transfer revealed a maximal PD-L1 expression on antigen-specific T cells within 3–4 hours after co-incubation with antigen-pulsed APCs, being detectable up to 72 hours. Antigen-pulsed immature DCs were less effective in transfering surface molecules such as PD-L1 onto CD8+ T cells after antigen-specific recognition. Using a transwell system we could show that the acquisition of PD-L1 requires cell-cell contact. Furthermore, PD-L1 cannot be acquired by T cells from a lysate of mDCs. The transfer process is impaired after pretreatment of T cells with concanamycin A, a specific inhibitor of vacuolar ATPases, playing an important role in membrane trafficking. Moreover, fixation of DCs with glutaraldehyde completely abrogated the acquisition of PD-L1 on T cells suggesting that an active interaction between APCs and T cells is required for trogocytosis. Of importance, CD8+ T cells which acquired PD-L1 complexes, were able to induce apoptosis of neighbouring PD-1 expressing CD8+ T cells, that could be completely blocked by an anti-PD-L1 antibody. In summary our data demonstrate for the first time that human antigen-specific CD8+ T cells take up functionally active PD-L1 from APCs in an antigen-specific fashion, leading to apoptosis of PD-1 expressing T cells. The transfer of functionally active co-inhibitory molecules from APCs onto human CD8+ T cells may serve to limit clonal expansion of antigen-specific T-cell responses but may also play a major role for T-cell exhaustion in chronic infection and tumor immunosurveillance. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Role of Type I Interferon Signaling in Human Metapneumovirus Pathogenesis and Control of Viral Replication

2015 ◽  
Vol 89 (8) ◽  
pp. 4405-4420 ◽  
Author(s):  
Andrew K. Hastings ◽  
John J. Erickson ◽  
Jennifer E. Schuster ◽  
Kelli L. Boyd ◽  
Sharon J. Tollefson ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Human Metapneumovirus ◽  
Type I ◽  
Type I Ifn ◽  
Inhibitory Receptor ◽  
Programmed Death ◽  
Hmpv Infection ◽  
Antigen Presenting

ABSTRACTType I IFN signaling, which is initiated through activation of the alpha interferon receptor (IFNAR), regulates the expression of proteins that are crucial contributors to immune responses. Paramyxoviruses, including human metapneumovirus (HMPV), have evolved mechanisms to inhibit IFNAR signaling, but the specific contribution of IFNAR signaling to the control of HMPV replication, pathogenesis, and adaptive immunity is unknown. We used IFNAR-deficient (IFNAR−/−) mice to assess the effect of IFNAR signaling on HMPV replication and the CD8+T cell response. HMPV-infected IFNAR−/−mice had a higher peak of early viral replication but cleared the virus with kinetics similar to those of wild-type (WT) mice. However, IFNAR−/−mice infected with HMPV displayed less airway dysfunction and lung inflammation. CD8+T cells of IFNAR−/−mice after HMPV infection expressed levels of the inhibitory receptor programmed death 1 (PD-1) similar to those of WT mice. However, despite lower expression of inhibitory programmed death ligand 1 (PD-L1), HMPV-specific CD8+T cells of IFNAR−/−mice were more functionally impaired than those of WT mice and upregulated the inhibitory receptor Tim-3. Analysis of the antigen-presenting cell subsets in the lungs revealed that the expansion of PD-L1lowdendritic cells (DCs), but not PD-L1highalveolar macrophages, was dependent on IFNAR signaling. Collectively, our results indicate a role for IFNAR signaling in the early control of HMPV replication, disease progression, and the development of an optimal adaptive immune response. Moreover, our findings suggest an IFNAR-independent mechanism of lung CD8+T cell impairment.IMPORTANCEHuman metapneumovirus (HMPV) is a leading cause of acute respiratory illness. CD8+T cells are critical for clearing viral infection, yet recent evidence shows that HMPV and other respiratory viruses induce CD8+T cell impairment via PD-1–PD-L1 signaling. We sought to understand the role of type I interferon (IFN) in the innate and adaptive immune responses to HMPV by using a mouse model lacking IFN signaling. Although HMPV titers were higher in the absence of type I IFN, virus was nonetheless cleared and mice were less ill, indicating that type I IFN is not required to resolve HMPV infection but contributes to pathogenesis. Further, despite lower levels of the inhibitory ligand PD-L1 in mice lacking type I IFN, CD8+T cells were more impaired in these mice than in WT mice. Our data suggest that specific antigen-presenting cell subsets and the inhibitory receptor Tim-3 may contribute to CD8+T cell impairment.

scholarly journals Durable antitumor responses to CD47 blockade require adaptive immune stimulation

2016 ◽  
Vol 113 (19) ◽  
pp. E2646-E2654 ◽  
Author(s):  
Jonathan T. Sockolosky ◽  
Michael Dougan ◽  
Jessica R. Ingram ◽  
Chia Chi M. Ho ◽  
Monique J. Kauke ◽  
...  
Keyword(s):  
Regulatory Protein ◽  
Antibody Therapy ◽  
Human Tumor ◽  
Adaptive Immune System ◽  
Immune Checkpoints ◽  
Adaptive Immune ◽  
Receptor Signal ◽  
Programmed Death ◽  
Antitumor Antibodies ◽  
Antitumor Antibody

Therapeutic antitumor antibodies treat cancer by mobilizing both innate and adaptive immunity. CD47 is an antiphagocytic ligand exploited by tumor cells to blunt antibody effector functions by transmitting an inhibitory signal through its receptor signal regulatory protein alpha (SIRPα). Interference with the CD47–SIRPα interaction synergizes with tumor-specific monoclonal antibodies to eliminate human tumor xenografts by enhancing macrophage-mediated antibody-dependent cellular phagocytosis (ADCP), but synergy between CD47 blockade and ADCP has yet to be demonstrated in immunocompetent hosts. Here, we show that CD47 blockade alone or in combination with a tumor-specific antibody fails to generate antitumor immunity against syngeneic B16F10 tumors in mice. Durable tumor immunity required programmed death-ligand 1 (PD-L1) blockade in combination with an antitumor antibody, with incorporation of CD47 antagonism substantially improving response rates. Our results highlight an underappreciated contribution of the adaptive immune system to anti-CD47 adjuvant therapy and suggest that targeting both innate and adaptive immune checkpoints can potentiate the vaccinal effect of antitumor antibody therapy.

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