CD8

CD8 T Cells

Diagram of the CD8 receptor

CD8 T cells, also known as cytotoxic T cells, are a subset of T cells that play a crucial role in the immune system by directly killing infected or cancerous cells. These cells are characterized by the presence of the CD8 glycoprotein on their surface, which serves as a co-receptor that enhances their ability to recognize antigens presented by MHC class I molecules.

Structure and Function

CD8 T cells are distinguished by the CD8 receptor, which is a dimeric protein composed of two chains, usually referred to as CD8_ and CD8_. This receptor is essential for the interaction with MHC class I molecules, which present endogenous antigens, typically derived from viral or tumor proteins.

The primary function of CD8 T cells is to eliminate cells that are infected with viruses or have become cancerous. Upon recognition of an antigen-MHC class I complex, CD8 T cells become activated and can induce apoptosis in the target cell through the release of cytotoxic granules containing perforin and granzymes.

Activation and Differentiation

CD8 T cell activation requires two signals: recognition of the antigen-MHC class I complex and a co-stimulatory signal provided by antigen-presenting cells (APCs). Once activated, CD8 T cells proliferate and differentiate into effector cells capable of killing target cells. Some of these cells will also become memory T cells, which provide long-term immunity by responding more rapidly upon re-exposure to the same antigen.

Role in Disease and Therapy

CD8 T cells are critical in controlling viral infections and are also involved in the immune response against tumors. However, their activity can also contribute to autoimmune diseases if they mistakenly target healthy cells. In cancer immunotherapy, strategies such as CAR T-cell therapy aim to enhance the activity of CD8 T cells against cancer cells.

Related pages

• T cell
• MHC class I
• Immune system
• Cytotoxicity
• Cancer immunotherapy