Cell-mediated immunity meaning

Cell-mediated immunity definitions

Cell-mediated immunity is a crucial component of the body's immune response, playing a vital role in defending against intracellular pathogens, such as viruses and some bacteria. This type of immunity involves the activation of T lymphocytes, also known as T cells, which are a type of white blood cell. T cells are produced in the bone marrow and mature in the thymus gland, which is why they are called T cells.

The Role of T Cells in Cell-Mediated Immunity

T cells are responsible for recognizing infected cells and destroying them. There are several types of T cells, including helper T cells, cytotoxic T cells, and regulatory T cells. Helper T cells help activate other immune cells, such as B cells and macrophages, to enhance the immune response. Cytotoxic T cells, on the other hand, directly attack and kill infected cells. Regulatory T cells play a role in controlling the immune response to prevent excessive inflammation and autoimmunity.

Antigen Presentation

One of the key steps in cell-mediated immunity is the process of antigen presentation. Antigens are molecules that are recognized by the immune system as foreign invaders. Antigen-presenting cells, such as dendritic cells and macrophages, engulf and process antigens from pathogens. They then present these antigens on their cell surface using major histocompatibility complex (MHC) molecules. T cells recognize these antigen-MHC complexes and become activated to mount an immune response.

Activation and Effector Function

When T cells encounter their specific antigen, they become activated and undergo clonal expansion, leading to the proliferation of antigen-specific T cells. Activated T cells differentiate into effector cells with specialized functions. Cytotoxic T cells release cytotoxic molecules, such as perforin and granzymes, to induce apoptosis in infected cells. Helper T cells secrete cytokines to stimulate and coordinate the immune response.

Cell-mediated immunity plays a critical role in the defense against intracellular pathogens and cancer cells. It is also involved in the rejection of transplanted tissues and the development of autoimmune diseases. Without the proper functioning of T cells, the body is more vulnerable to infections and other diseases.

In summary, cell-mediated immunity is a complex and tightly regulated process that involves the activation and coordination of T cells to eliminate infected or abnormal cells. Understanding the mechanisms of cell-mediated immunity is essential for developing new treatments and vaccines to combat a wide range of diseases.

Cell-mediated immunity Examples

1. During a viral infection, cell-mediated immunity plays a crucial role in fighting off the infected cells.
2. Organ transplant recipients often require immunosuppressant drugs to prevent rejection by cell-mediated immunity.
3. Cancer immunotherapy aims to enhance cell-mediated immunity to target and destroy tumor cells.
4. Individuals with compromised cell-mediated immunity are more susceptible to opportunistic infections.
5. Vaccines work by stimulating the immune system, including cell-mediated immunity, to provide protection against specific pathogens.
6. Autoimmune diseases can result from a breakdown in self-tolerance mechanisms of cell-mediated immunity.
7. Tuberculosis is an infectious disease that primarily affects the lungs and is controlled by cell-mediated immunity.
8. Research is ongoing to develop novel therapies that target cell-mediated immunity for the treatment of autoimmune disorders.
9. HIV targets and impairs the function of cells involved in cell-mediated immunity, leading to a weakened immune response.
10. Allergic reactions can involve an inappropriate activation of cell-mediated immunity against harmless substances.

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