Cell-mediated immuniyy
Relies on lymphocytes, not antibodies. Helper T cells regulate the production of antibodies by B cells. Other T cells attack antigen-bearing cells directly.
Cell-mediated immunity is a branch of the immune system that involves the activation of T cells (also known as T lymphocytes). T cells are a type of white blood cell that are responsible for identifying and responding to specific pathogens or foreign antigens in the body.
During cell-mediated immunity, T cells recognize antigen-presenting cells (APCs) that display foreign antigens on their surface. This recognition stimulates the T cells to divide and differentiate into effector cells that attack and eliminate the invading pathogen. There are two main types of T cells involved in cell-mediated immunity:
1. Cytotoxic T cells (also known as CD8+ T cells) – These T cells directly attack and destroy infected cells that display the foreign antigen on their surface. Cytotoxic T cells release molecules such as perforin and granzyme, which cause cell death in the infected cell.
2. Helper T cells (also known as CD4+ T cells) – These T cells do not directly attack pathogens. Instead, they help other immune cells (such as B cells and cytotoxic T cells) to mount an effective immune response against the pathogen. Helper T cells release cytokines that activate and stimulate the immune response.
Cell-mediated immunity is particularly effective against intracellular pathogens such as viruses, bacteria, and fungi that have infected cells in the body. It is also involved in the rejection of transplanted tissues and in the development of autoimmune diseases.
Overall, cell-mediated immunity plays a critical role in protecting the body against invading pathogens and maintaining proper immune function.
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