PD-1 Receptor – Function & Immunotherapy
The PD-1 receptor is an immune checkpoint protein on T cells that regulates immune responses. Cancer cells exploit it to evade the immune system, making it a key target in modern immunotherapy.
Things worth knowing about "PD-1 receptor"
The PD-1 receptor is an immune checkpoint protein on T cells that regulates immune responses. Cancer cells exploit it to evade the immune system, making it a key target in modern immunotherapy.
What is the PD-1 Receptor?
The PD-1 receptor (Programmed Cell Death Protein 1) is an immune checkpoint protein expressed on the surface of T cells and other immune cells. It was discovered in the early 1990s and plays a pivotal role in regulating the human immune response.
PD-1 belongs to the CD28 receptor family and is encoded by the PDCD1 gene. Its primary function is to prevent excessive immune activation, thereby maintaining a balance between effective immune defense and protection against autoimmune diseases.
Mechanism of Action
The PD-1 receptor is activated when it binds to its specific ligands – PD-L1 (Programmed Death-Ligand 1) or PD-L2 – which are expressed on various body cells and, critically, on tumor cells.
When PD-1 binds to PD-L1 or PD-L2, inhibitory signals are transmitted into the T cell, resulting in:
- Reduced T cell activity and proliferation
- Decreased cytokine production (signaling molecules of the immune system)
- Increased T cell exhaustion in chronic disease states
- Promotion of immune tolerance toward the body's own tissues
Under normal circumstances, this mechanism is essential for preventing autoimmune reactions. In cancer, however, tumor cells exploit this pathway to evade detection and destruction by the immune system.
Significance in Oncology
Many cancer cells overexpress the ligand PD-L1, enabling them to suppress T cell activity and escape immune surveillance. This mechanism of immune evasion has been documented across numerous tumor types, including:
- Non-small cell lung cancer (NSCLC)
- Malignant melanoma (skin cancer)
- Renal cell carcinoma
- Bladder cancer (urothelial carcinoma)
- Hodgkin lymphoma
- Head and neck squamous cell carcinoma
The discovery of this mechanism laid the foundation for the development of a new class of cancer drugs known as checkpoint inhibitors.
PD-1 Inhibitors as Immunotherapy
Based on the PD-1 receptor, monoclonal antibodies have been developed that block the receptor or its ligands, thereby restoring the immune response against tumor cells. These agents are known as PD-1 inhibitors or anti-PD-1 antibodies.
Approved PD-1 Inhibitors (Examples)
- Pembrolizumab (Keytruda®): directly blocks PD-1
- Nivolumab (Opdivo®): directly blocks PD-1
- Atezolizumab (Tecentriq®): blocks PD-L1
- Durvalumab (Imfinzi®): blocks PD-L1
These agents have revolutionized the treatment of various cancers and, in some cases, have led to durable remissions even in advanced disease stages.
Role in Autoimmune Diseases and Infectious Diseases
Beyond oncology, the PD-1 receptor is also significant in other medical contexts:
- Autoimmune diseases: Deficient PD-1 signaling can increase susceptibility to autoimmune conditions such as systemic lupus erythematosus or rheumatoid arthritis.
- Chronic infections: In diseases such as HIV or chronic hepatitis B, elevated PD-1 expression on exhausted T cells impairs immune control of the infection.
- Transplant medicine: The PD-1 axis plays a role in promoting tolerance toward transplanted organs.
Side Effects of PD-1 Blockade
Because PD-1 inhibitors broadly activate the immune system, they can also attack healthy tissues. Typical immune-mediated adverse effects include:
- Skin rash and itching (dermatitis)
- Lung inflammation (pneumonitis)
- Liver inflammation (hepatitis)
- Thyroid dysfunction (hypothyroidism or hyperthyroidism)
- Intestinal inflammation (colitis)
- Rarely: inflammation of the heart (myocarditis) or nervous system
These side effects require close medical monitoring and are treated with corticosteroids when necessary.
Diagnostic Relevance: PD-L1 Testing
Before initiating checkpoint inhibitor therapy, the PD-L1 expression in tumor tissue is assessed by immunohistochemistry (IHC) in many cancer types. A high PD-L1 score may indicate a better response to therapy, although it is not the sole predictive biomarker.
References
- Ishida Y. et al. - Induced expression of PD-1, a novel member of the immunoglobulin gene superfamily, upon programmed cell death. EMBO Journal, 11(11):3887-3895, 1992.
- Topalian SL, Drake CG, Pardoll DM. - Immune checkpoint blockade: a common denominator approach to cancer therapy. Cancer Cell, 27(4):450-461, 2015. PubMed PMID: 25858804.
- World Health Organization (WHO) - Cancer Overview and Immunotherapy. Available at: https://www.who.int/news-room/fact-sheets/detail/cancer
Building Blocks for a Healthy Life
As an integrated manufacturer, we develop & produce evidence-based, patented, and non-patented formulations. We work exclusively with plant and natural extracts according to the strictest purity & quality standards.
The combination of science & modern technology with the laws of nature creates solutions consistently tailored to humans – for the highest good: health.
Verwandte Produkte
For Healthy Oral Flora & Dental Care
Formulated lozenges with Dentalac®, lactic acid bacteria, and Lactoferrin CLN®
For Healthy Oral Flora & Dental Care
Formulated lozenges with Dentalac®, lactic acid bacteria, and Lactoferrin CLN®
For your universal protection
As one of the most valuable proteins in the body, lactoferrin is a natural component of the immune system.
For your iron balance
Specially formulated for your iron balance with plant-based curry leaf iron, Lactoferrin CLN®, and natural Vitamin C from rose hips.