Immune checkpoint proteins play a central role in regulating the activities of different immune cell types. These molecules have either stimulatory functions that promote immune cell activation to protect the host from invading pathogens and developing malignancies, or inhibitory functions that suppress immune cell activation to dampen inflammation, maintain immune homeostasis, and prevent tissue damage. Tumor cells frequently exploit immune checkpoint pathways by up-regulating the expression of ligands that activate inhibitory receptors on different immune cell types, allowing them to evade destruction by the host’s immune system. As a result, researchers have focused on targeting immune checkpoint molecules for cancer immunotherapy using either agonists of immune cell stimulatory receptors to drive immune cell activation or antagonists of inhibitory receptors to promote immune checkpoint blockade. While remarkable success has been achieved by targeting the T cell co-inhibitory receptors, CTLA-4 and PD-1, clinicians have also found that monoclonal antibodies directed against CTLA-4, PD-1, or the PD-1 ligand, PD-L1, are only effective in a minority of cancer patients and some patients that initially respond to treatment with these antibodies, can become resistant or relapse due to an up-regulation of other immune checkpoint pathways. Therefore, additional immune checkpoint regulators that may serve as immunotherapeutic targets, either alone or in combination, are being sought.
How Cancer Circumvents the Immune System
免疫检查点蛋白靶标
B7-CD28 家族
B7-CD28 家族
免疫检查点蛋白 B7 家族成员与 CD28 家族受体结合，在 T 细胞受体 (TCR) 识别抗原肽/MHC 后促进或抑制 T 细胞激活。B7 和 CD28 家族包括免疫检查点蛋白 PD-L1、PD-1 和 CTLA-4，它们是癌症免疫治疗中研究最多的靶标。
犬尿氨酸通路
犬尿氨酸通路
通过犬尿氨酸通路减少色氨酸和犬尿氨酸的生成，可抑制 T 细胞和自然杀伤细胞的功能，促进调节性 T 细胞的产生。由于肿瘤细胞或肿瘤微环境中的细胞可大量表达 IDO 和 TDO2，这是两种可催化该通路中的初始和限速步骤的关键酶，因此，人们正在研究将这些分子的抑制剂作为免疫治疗药物的可能性。
LAG-3
LAG-3
LAG-3 是一种抑制性免疫检查点受体，可负向调节 T 细胞活性并促进调节性 T 细胞的抑制活性。该受体在癌症中耗竭的 T 细胞和自然杀伤细胞上表达上调，这被认为是导致这些细胞功能障碍的原因，因此，免疫肿瘤学研究人员将该受体作为他们的一个研究目标。
LLRB 受体家族
LLRB 受体家族
LILRB 亚家族成员是免疫检查点受体，激活后可抑制多种类型免疫细胞的功能。免疫肿瘤学研究人员正在研究这些受体及其配体，因为在肿瘤微环境中的肿瘤细胞或免疫细胞上，它们的表达上调，可使得肿瘤可逃避免疫检测。
TIGIT、DNAM-1、CD96 和 PVRIG
TIGIT、DNAM-1、CD96 和 PVRIG
TIGIT、DNAM-1、CD96 和 PVRIG 是免疫检查点受体，它们竞争结合 CD155/PVR 和/或 CD112/Nectin-2 配体，可抑制淋巴细胞的功能。DNAM-1/CD226 为共刺激受体，TIGIT、PVRIG 和 CD96 为 T 细胞和自然杀伤细胞上的共抑制受体。因此，研究人员正在对这些蛋白质展开研究，期望能将它们作为癌症免疫治疗的靶标。
TIM-3
TIM-3
TIM-3 在 CD8+ T 细胞和自然杀伤细胞上的高水平表达与耗竭表型相关，其在肿瘤相关的 FoxP3+ 调节性 T 细胞 (Treg) 上的表达，标志着 Treg 的一个子集具有增强的抑制功能和恢复能力。考虑到这些特征，免疫肿瘤学研究人员正在研究 TIM-3 阻断，以确定它们能否改善抗肿瘤免疫应答。
TNF 受体超家族共刺激分子
TNF 受体超家族共刺激分子
作为通过免疫检查点阻断恢复抗肿瘤免疫应答的替代方法，共刺激免疫检查点受体的激动剂也正处于探索之中。其中许多受体是 TNF 受体超家族成员，并已被证明参与了增强 T 细胞和/或自然杀伤细胞的增殖和效应子功能。
R&D Systems Immune Checkpoint Proteins Are Rigorously Tested to Ensure Lot-to-Lot Consistency
R&D Systems Recombinant Human PD-1 Displays High Lot-to-Lot Consistency. Two independent lots of Recombinant Human PD-1 (R&D Systems, Catalog # 8986-PD) immobilized at 1 ug/mL were tested for their ability to bind to increasing concentrations of Recombinant Human PD-L1/B7-H1 Fc Chimera (R&D Systems, Catalog # 156-B7) in a functional ELISA. The concentration of Recombinant Human PD-L1/B7-H1 Fc Chimera that produces 50% of the optimal binding response is approximately 0.3-1.8 ug/mL. Each trace on the graph represents data obtained from Recombinant Human PD-1 from a different manufacturing run, demonstrating the lot-to-lot consistency of the protein.
Protein Characterization Using SEC-MALS Analysis
Recombinant Human PD‑1 Fc Chimera Protein SEC-MALS. Recombinant human PD-1/Fc (Catalog # 1086-PD) has a molecular weight (MW) of 125.1 kDa as analyzed by SEC-MALS, suggesting that this protein is a homodimer. MW may differ from predicted MW due to post-translational modifications (PTMs) present (i.e. Glycosylation).
| SEC-MALS Data | Result |
| Retention Time | 14.7-15.2 min |
| MW-Predicted (Monomer) | 42.6 kDa |
| MW-MALS | 125.1 kDa |
| Polydispersity | 1.001 |
| System Suitability: BSA Monomer 66.4 ± 3.32 kDa | Pass |
Analysis of the Binding Properties of R&D Systems Avi-tag Biotinylated Immune Checkpoint Proteins
Affinity Measurements and Binding Kinetics of the CD155/PVR:TIGIT Protein Interaction by Surface Plasmon Resonance. Sensorgram data of captured Avi-tag Biotinylated Recombinant Human CD155/PVR Fc Chimera (R&D Systems, Catalog # AVI9174) binding to Recombinant Human TIGIT His-tag (R&D Systems, Catalog # 9525-TG). The corresponding overlaid kinetic fits with the residual plot shown below. The concentration of Recombinant Human TIGIT His-tag ranged from 0.2 nM to 400 nM. The corresponding steady state affinity fit is shown at the bottom. The experiment was performed on a Biacore T200, GE Healthcare.
Affinity Measurements and Binding Kinetics of the PD-1:PD-L1 Interaction by Surface Plasmon Resonance. Sensorgram data of captured Avi-tag Biotinylated Recombinant Human PD-L1 His tag (R&D Systems, Catalog # AVI9049) binding to Recombinant Human PD-1 His tag (R&D Systems, Catalog # 8986-PD). The corresponding overlaid kinetic fits with the residual plot shown below. The concentration of Recombinant Human PD-1 His-tag ranged from 3.2 nM to 13.2 μM. The corresponding steady state affinity fit is shown below. The experiment was performed on a BiacoreT200, GE Healthcare.
Affinity Measurements and Binding Kinetics of the CTLA-4:B7-1 Interaction by Surface Plasmon Resonance. Sensorgram data of captured Avi-tag Biotinylated Recombinant Human CTLA-4 Fc Chimera (R&D Systems, Catalog # AVI7268) binding to Recombinant Human B7-1 Fc Chimera (R&D Systems, Catalog # 10133-B1). Briefly, Avi-tag Biotinylated Recombinant Human CTLA-4 Fc Chimera was captured at a low coupling density to the active flow cell via the Avi-tag biotin. Recombinant Human B7-1 Fc Chimera at a concentration range between 82 pM and 21 nM was flowed over both active and uncoupled reference flow cells at each concentration. Kinetic sensorgrams were fit to a 1:1 binding model to determine the binding kinetics and affinity, with an interaction affinity of KD=0.2511 nM. The corresponding overlaid kinetic fits with the residual plot shown below. The corresponding steady state affinity fit is shown at the bottom. The experiment was performed on a Biacore T200, GE Healthcare.
Affinity Measurements and Binding Kinetics of the CD47:SIRP alpha Interaction by Surface Plasmon Resonance. Sensorgram data of captured Avi-tag Biotinylated Recombinant Human CD47 Fc tag (R&D Systems, Catalog # AVI4670) binding to Recombinant Human SIRP alpha His tag (R&D Systems, Catalog # 9378-SA). The corresponding overlaid kinetic fits with the residual plot shown below. The concentration of Recombinant Human SIRP alpha His-tag ranged from 6.85 nM to 3.51 μM. The corresponding steady state affinity fit is shown at the bottom. The experiment was performed on a Biacore T200, GE Healthcare.
下载我们当前和新出现的免疫检查点靶标电子书
在调节不同类型免疫细胞的活性方面，免疫检查点蛋白发挥着核心作用，是肿瘤免疫治疗中一些最有前景的靶标。本电子书重点介绍了一些正被作为免疫肿瘤学靶标进行研究的免疫检查点分子，以及我们提供的用于研究这些分子的产品。
免疫检查点研究的相关产品和资源
用于评估蛋白质纯度的 Maurice™ CE-SDS
用于评估蛋白质纯度的 Maurice™ CE-SDS
虽然在工业上，SDS-PAGE 仍被用于进行蛋白质纯度分析，但其在灵敏度、重现性和半定量性质方面具有自限性。作为替代方案，我们提供了全自动 Maurice 毛细管电泳 (CE)-SDS 系统。本应用说明概述了相较于标准 SDS-PAGE 分析，Maurice 在蛋白质纯度测定方面的优势。
RNAscope™ In Situ Hybridization Assay
RNAscope™ In Situ Hybridization Assay
RNAscope 技术能够快速高效地检测任何靶标 mRNA 的共表达谱，包括免疫检查点靶标和免疫细胞标志物，在福尔马林固定石蜡包埋 (FFPE) 组织中具有单分子灵敏度和高特异性。该技术可与免疫组织化学或免疫荧光技术结合，在同一玻片上同时检测靶标 RNA 和蛋白质。
肿瘤机制详图
肿瘤机制详图
肿瘤微环境 (TME) 在抑制抗肿瘤免疫应答中起核心作用。使用我们全新的海报，了解肿瘤细胞、肿瘤源性外泌体、调节性 T 细胞、髓源性抑制细胞 (MDSC) 和肿瘤相关巨噬细胞 (TAM) 在 TME 中介导免疫抑制的关键机制。
适用于免疫检查点靶标的 Avi-tag 生物素化蛋白
适用于免疫检查点靶标的 Avi-tag 生物素化蛋白
生物素化蛋白是评估蛋白质相互作用或为潜在治疗药物筛选抗体或小分子库的有力工具。我们现提供各种适用于免疫检查点靶标的 Avi-tag 生物素化重组蛋白。
使用 Wes™ 和 Milo™ 分析 TME 中的免疫细胞群
使用 Wes™ 和 Milo™ 分析 TME 中的免疫细胞群
分析肿瘤微环境 (TME) 中的免疫细胞组成和功能，可以改善机体对免疫治疗的应答，并发现新的治疗靶标。本应用说明概述了如何将 Wes 上的 Simple Western™ 测定与 Milo 上的 Single-Cell Westerns™ 配合使用，以分析您样本中的免疫细胞群。
用于鉴定免疫细胞类型的经流式细胞术验证的抗体
用于鉴定免疫细胞类型的经流式细胞术验证的抗体
Bio-Techne 旗下品牌 R&D Systems 和 Novus Biologicals 致力于提供质量出众的抗体，以支持您的研究。使用我们品类繁多的经流式细胞术验证的抗体来分析免疫检查点蛋白或其配体的表达。
Two Sides of A Coin: CTLA-4 in Immunotherapy and Autoimmunity
CTLA-4 can be a double-edged sword in the fight against cancer. Get accurate and consistent CTLA-4 data with Quantikine ELISAs.
