T-Cell

T-Cell

A T-cell or T lymphocyte is a type of white blood cell that plays a central role in the immune system. T-cells are one of two primary types of lymphocytes—B cells being the second type—that determine the specificity of immune response to antigens (foreign substances) in the body.

Function

T-cells are involved in cell-mediated immunity, one of the two primary responses of the adaptive immune system. They differentiate into various types based on their function. These include Helper T cells, Cytotoxic T cells, Memory T cells, and Regulatory T cells.

Helper T cells

Helper T cells assist in the immune response by recognizing the presence of a foreign antigen and then stimulating the immune response by producing cytokines and stimulating other immune cells, such as macrophages, B cells, and Cytotoxic T cells.

Cytotoxic T cells

Cytotoxic T cells are responsible for killing infected cells. They are also known as CD8+ T cells because they express the CD8 glycoprotein at their surface.

Memory T cells

Memory T cells are a subset of antigen-specific T cells that persist long-term after an infection has resolved. They quickly expand to large numbers of effector T cells upon re-exposure to their cognate antigen, thus providing the immune system with "memory" against past infections.

Regulatory T cells

Regulatory T cells are crucial for the maintenance of immunological tolerance. Their major role is to shut down T cell-mediated immunity toward the end of an immune reaction and to suppress auto-reactive T cells that escaped the process of negative selection in the thymus.

Development

T-cells originate from hematopoietic stem cells in the bone marrow. These progenitor cells migrate to the thymus, where they undergo a process of maturation, which includes both the proliferation of antigenically committed cells and the elimination of cells that are capable of reacting with self-antigens (negative selection).

Clinical significance

T-cells play a crucial role in the immune response to viral infections and cancer. They are also implicated in a variety of disease processes, including autoimmune diseases, transplant rejection, severe immune deficiencies, and allergic reactions.