Precision Medicine
Flow Cytometric Assays

Flow Cytometry


Immune Checkpoint Analysis

Immune checkpoints are important regulatory molecules and pathways that help maintain immune homeostasis and prevent autoimmunity. Studying immune checkpoint regulators are of immense importance due to their clinical relevance in pathologies, particularly in the context of cancer. Cancer immunotherapies develop and utilise inhibitors of immune checkpoints to initiate host immune responses against the tumour. Immune checkpoint analysis can help predict treatment responses, aid biomarker discovery, uncover mechanisms of resistance and help develop personalised medicine from understanding the immune profile of the patient. PeploBio offers flow cytometric expression analysis on a panel of immune checkpoint inhibitors of great interest in clinical studies.
Cytotoxic T-Lymphocyte Associated Protein 4 (CTLA4): blocks autoreactive naïve T-cells during activation. CTLA4 is required for Treg function. Tumour cells use the CTLA4 pathway to reduce T-cell proliferation and activation [1].
Programmed Cell Death Protein 1 (PD1): prevents phosphorylation of TCR signalling proteins which reduces the activity, proliferation, and survival of T-cells. Exhausted T-cells expressing PD1 are characteristic in cancer and chronic infections [1, 2].
Programmed Death-Ligand 1 (PDL1): inhibits T-cell responses via Treg induction [2].
OX40 (CD134): stimulates T-cell expansion and proliferation. OX40 can reduce Treg immunosuppression to enhance anti-tumour immunity [3].
Glucocorticoid Induced TNFR Related Protein (GITR): enhances effector T-cell function, reduces Treg function and exhibits anti-tumour activity [4].
Indoleamine 2, 3-Dioxygenase (IDO): is an enzyme that generates T-cell inhibiting metabolites and promotes Tregs [5].
Cluster of Differentiation 73 (CD73): CD73 induced adenosine dampens effector T-cell response, promotes immunosuppression and angiogenesis [6].
Cluster of Differentiation 137 (CD137): promotes NK cells, monocyte, macrophage, and T-cell anti-tumour response [7].
Signalling Lymphocytic Activation Molecule Family Member 7 (SLAMF7): SLAMF7-EAT2 interaction activates immune response. SLAMF7 signalling in absence of EAT2 inhibits cells [8].
Killer Immunoglobulin-like Receptor (KIR): HLA class I interaction with inhibitory KIRs inhibits NK cells and induces immune tolerance. Malignant tumours upregulate KIRs [9].
V-domain Ig Suppressor of T-cell Activation (VISTA): suppresses T-cell activation, proliferation, and cytokine production [5].
T-cell Immunoglobulin and Mucin-Domain Containing 3 (TIM3): may be a costimulatory or a coinhibitory receptor depending on context. Blocking TIM3 signalling improves anti-tumour T cell activity [5].
Lymphocyte Activation Gene 3 (LAG3): LAG3 binds to MHC II to reduce T-cell activity [5].

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[1] Buchbinder EI, Desai A. CTLA-4 and PD-1 pathways: similarities, differences, and implications of their inhibition. American journal of clinical oncology. 2016 Feb;39(1):98.
[2] Kazanova A, Rudd CE. Programmed cell death 1 ligand (PD-L1) on T cells generates Treg suppression from memory. PLoS Biology. 2021 May 19;19(5):e3001272.
[3] Deng J, Zhao S, Zhang X, Jia K, Wang H, Zhou C, He Y. OX40 (CD134) and OX40 ligand, important immune checkpoints in cancer. OncoTargets and therapy. 2019;12:7347.
[4] Buzzatti G, Dellepiane C, Del Mastro L. New emerging targets in cancer immunotherapy: the role of GITR. ESMO open. 2019 Jan 1;4:e000738.
[5] Popp FC, Capino I, Bartels J, Damanakis AI, Li J, Datta RR, Löser H, Zhao Y, Quaas A, Lohneis P, Bruns CJ. Expression of immune checkpoint regulators IDO, VISTA, LAG3, and TIM3 in resected pancreatic ductal adenocarcinoma. Cancers. 2021 May 29;13(11):2689.
[6] Turiello R, Pinto A, Morello S. CD73: a promising biomarker in cancer patients. Frontiers in pharmacology. 2020 Nov 16;11:609931.
[7] Stoll A, Bruns H, Fuchs M, Völkl S, Nimmerjahn F, Kunz M, Peipp M, Mackensen A, Mougiakakos D. CD137 (4-1BB) stimulation leads to metabolic and functional reprogramming of human monocytes/macrophages enhancing their tumoricidal activity. Leukemia. 2021 Dec;35(12):3482-96.
[8] O’Connell P, Pepelyayeva Y, Blake MK, Hyslop S, Crawford RB, Rizzo MD, Pereira-Hicks C, Godbehere S, Dale L, Gulick P, Kaminski NE. SLAMF7 Is a Critical Negative Regulator of IFN-α–Mediated CXCL10 Production in Chronic HIV Infection. The Journal of Immunology. 2019 Jan 1;202(1):228-38. [9] Xu Y, Wang L, Li W, Chen B, Liu Y, Wang H, Zhao S, Ye L, He Y, Zhou C. Killer immunoglobulin-like receptors/human leukocyte antigen class-I, a crucial immune pathway in cancer. Annals of translational medicine. 2020 Mar;8(5).

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