The immune system is one of the most intricate and important aspects of the human body. It is the main internal defense against harmful antigens and pathogens that lead to various diseases.
Advances in immunology, or the study of the immune system, have led to novel treatments for serious illnesses like cancer. To develop these therapies, one must first look at the key elements of the body’s immune response. The use of T cells in immunology research, in particular, has led to the discovery of new approaches for treating cancer.
This guide provides an in-depth look at T cells, including their essential functions within the immune system and role in immunology research.
Where Do T Cells Come From?
Within the body’s bone marrow, cells known as hematopoietic stem cells (HSCs) exist as the precursor to all the cells in the immune system. HSCs give rise to two lines of cells: lymphoid cells — to which T Cells trace their lineage — and myeloid cells, such as platelets and red blood cells.
In addition to T Cells, the other major types of lymphoid cells include B Cells and NK cells. Although these cells perform very different functions within immune system, they appear similar under a microscope due to their characteristically large round nuclei. In terms of cell frequency in peripheral blood, T cells are the most common comprise between 8% – 25% of all circulating leukocytes (immune cells). B cells are the second most common at 3% – 10%, followed by NK cells at 2% – 5%.
How T Cells Work
T cells are a major component of the adaptive immune system, which is activated by exposure to pathogens and uses immunological memory to prevent repeat infections.
T cells spend time maturing and evolving in the thymus gland. That is where they get the name “T” cell or “thymus-derived” cell. T cells adapt to the needs of the immune system throughout a person’s development.
When a child is born, their T cells play a critical role in immunity development and long-term defense to common pathogens. Around puberty, T cells begin to function more as immune regulators and general surveillance. As the body ages, T cells adopt a seek and destroy function, attacking tumors and other harmful cells.
Types of T Cells
Many different types of T cells play various roles in maintaining the homeostasis of the immune system. The two main types are cytotoxic T cells and helper T cells. However, regulatory T cells, memory T cells, and natural killer T cells also play an integral part in the immune response.
Cytotoxic T cells: These are the cells that most people imagine when they think of the immune system. Cytotoxic T cells are the warriors of the body’s immune response. They directly attack and destroy foreign bodies such as viruses, bacteria, and cancerous cells.
Helper T cells: These are the immune response organizers. They recruit B cells to produce antibodies and utilize cytokines to direct the rest of the immune system.
Role of T Cells in Long-term Health
Once an immune response is triggered, T cells jump into action, performing their different roles to effectively eradicate the pathogens or infected cells in the body. However, T cells are susceptible to exhaustion when activated for prolonged periods.
T cell exhaustion affects the cell’s ability to continue to function. Stimuli that normally call the immune system’s defenders into action, cease to be effective.
This happens most often when the body’s immune response is activated for extended periods of time, such as in cancer patients. According to the National Institutes of Health, researchers have identified certain proteins and transcription factors that are prevalent in patients with chronic conditions that essentially “turn off” the T cells.
Addressing T cells exhaustion is an important consideration when developing effective immunotherapies for cancer and other diseases.
Human PBMCs, in particular isolated T cells, are important tools for immunology research. They are fundamental to understanding different aspects of pathology and biology. As such, researchers have used T cells in numerous studies to develop novel treatments for various immune-related diseases.
Some cancer cells have an uncanny ability to suppress the immune system’s response. They do this by binding to partner proteins on the surface of T cells. These proteins are called immune checkpoint proteins, and, when they bind with their partner proteins, send an “off” signal to the T cells that make the tumor appear harmless. This allows the cancer cells to continue to multiply and spread unchecked.
Checkpoint inhibitors work by blocking the checkpoint proteins from binding with their partner proteins. This action, in turn, prevents the “off” switch on the T cells from being triggered. T cells are then able to correctly identify cancer and destroy it naturally.
CAR T Cells
Another immunotherapy approach that has proved quite effective at treating cancer is called adoptive cell transfer (ACT). The method known as CAR T cell therapy is the most advanced and researched ACT therapy.
CAR T cell therapy is currently used to treat hematologic cancers like leukemia and lymphoma. Blood from the patient is used to extract T cells, which are then genetically engineered to express special structures on their surfaces called chimeric antigen receptors (CARs). These CARs enable the T cells to identify and destroy cancer cells.
CAR T cell therapy has also been utilized in patients with HIV. Although it has thus far been unable to cure the disease, it has been shown to boost immune response and eliminate HIV latently infected cells in combination with antiretroviral therapy. Further research is required to uncover the full potential of CAR T cell treatment in HIV+ patients.
T cell response also plays a role in asthma. Asthma is caused by a hypersensitive immune response to a particular stimulus. Using T cell biomarkers, scientists are hoping to develop person-specific solutions to asthmas.
T Cells for Research
T cells are responsible for identifying pathogens, mounting immune responses, and eradicating harmful agents in the body. The use of T cells in immunology research has led to multiple advances in the treatment of cancer and other autoimmune diseases.
Cytologics provides academic and biopharmaceutical researchers with a range of immune cells, all of which adhere to strict quality standards. Our products include human PBMCs, B cells, T cells, monocytes, NK cells, and neutrophils.
Looking to advance your research? Contact us to find out more about how we can help.