T lymphocytes

T lymphocytes or T cells are a type of white blood cell that play a central role in cell-mediated immunity. They are named after the thymus, an organ where their final stage of development occurs.

Overview

T cells are a type of lymphocyte, which in turn are one of the five main types of white blood cell. They are an essential part of the immune system, and are particularly important for fighting against cellular pathogens, such as viruses and cancer cells.

Development

T cells originate from hematopoietic stem cells in the bone marrow. These cells migrate to the thymus, where they undergo a process of maturation. This process involves the expression of specific cell surface receptors, which allow the T cells to recognize and respond to specific antigens.

Types of T cells

There are several different types of T cells, each with a specific function in the immune response. These include:

• Helper T cells: These cells assist in the immune response by secreting cytokines, which stimulate other immune cells to respond to the infection.
• Cytotoxic T cells: These cells are capable of directly killing infected cells. They do this by recognizing antigens presented on the surface of the infected cells and releasing cytotoxic substances that cause the cell to die.
• Regulatory T cells: These cells help to control the immune response and prevent it from attacking the body's own cells. They do this by suppressing the activity of other T cells that are responding to the same antigen.
• Memory T cells: These cells remember specific antigens and can mount a faster and stronger response if the same antigen is encountered again in the future.

Role in disease

T cells play a crucial role in many diseases. In autoimmune diseases, T cells mistakenly attack the body's own cells, leading to tissue damage. In cancer, T cells often fail to recognize or effectively kill cancer cells, allowing the disease to progress. In HIV/AIDS, the virus specifically targets and destroys helper T cells, leading to a progressive weakening of the immune system.

See also

• Immune system
• White blood cell
• Lymphocyte
• Thymus
• Antigen
• Cytokine
• Autoimmune disease
• Cancer
• HIV/AIDS