Cellular immunity is an integral part of the body's immune response and is responsible for both short-term and long-term protection against infection. This article will provide an overview of this vital aspect of the immune response, discussing the major players in cellular immunity, including antigen presenting cells and T and B cells, as well as the mechanisms by which these cells work together to protect the body from infection. Understanding cellular immunity can help us better protect ourselves against a variety of diseases and other health issues.
Cellular immunity is a type of adaptive immune response that uses specialized white blood cells called T and B cells to protect the body from viruses, bacteria and other foreign particles. It is important to differentiate between cellular immunity and humoral or antibody-mediated immunity. Cellular immunity is triggered when antigen-presenting cells present antigens to the immune system, which initiates the activation of the T and B cells.
The T cells respond to antigens by releasing cytokines, which stimulate other cells to do their job in killing off infected cells or producing antibodies. The B cells, on the other hand, are more involved in producing antibodies which bind to the antigen and mark it for destruction by the immune cells.
The main function of cellular immunity is to recognize and destroy pathogens, and it is vital to maintaining the health of the body by preventing infections. It is also important for recognizing and eliminating cancer cells, as well as stimulating the production of antibodies. Cellular immunity works in combination with humoral immunity to provide a comprehensive defense system against foreign particles and diseases.
Antigen presenting cells (APCs) are essential components of cellular immunity. They function to identify, capture, and process antigens and present the processed antigen to T cells in order to initiate an adaptive immune response. APCs act as gatekeepers, ensuring that only legitimate, non-self antigens are presented to T cells, while self-antigens are ignored.
Types of APCs include professional APCs, such as dendritic cells, and non-professional APCs, such as macrophages. Professional APCs specialize in the capture, processing, and presentation of antigens to the immune system, whereas non-professional APCs specialize in phagocytosis and destruction of pathogens.
When an APC encounters a foreign antigen, it is engulfed and broken down into small peptides that are then presented on its surface bound to MHC proteins. The peptides presented on the APC's surface can then be recognized by T cells, leading to the activation of antigen-specific T cells. This binds with the T cell’s cell-surface receptors, initiating a chain of events that results in an effective immune response. Activated T cells can then go on to produce various effector molecules that destroy the pathogen or tumor cell.
Cellular immunity works by relying on two major types of immune cells: T-cells and B-cells. T-cells are the major players in cellular immunity, as they have direct contact with infected cells and recognize the antigen present. They can then activate a cascade of anti-viral responses, such as the production of cytokines which recruit other immune cells to the site of infection. B-cells, on the other hand, produce antibodies that can bind to antigens and mark them for destruction. B-cells help activate T-cells and other immune cells to create an effective immune response.
When it comes to attacking viruses, T-cells and B-cells use different mechanisms of action. T-cells first identify and “remember” foreign antigens, and then use specialized receptor molecules to recognize those antigens. Once the antigen is identified, the T-cell sends signals to the B-cells, which then produce antibodies to bind to the antigen and mark it for destruction. In addition, T-cells are able to directly target and destroy infected cells, while B-cells can help regulate the immune response by producing molecules which activate other immune cells to join in the attack.
The T-cell/B-cell combination is essential for initiating and regulating the adaptive immune response. It is the precise orchestrated action between these two cell types which make cellular immunity so effective at protecting us from infection.