Adaptive Immune System
The adaptive immune response is often considered the second line of defence the body has against infection. As its name suggests, the response is “adapted” depending on the specific pathogen present and it allows the development of immunological memory to prevent re-infection. The end point of this response is the production of antigen-specific antibodies to target pathogens.
T cells form a major part of the adaptive immune response but they can only recognise antigens when they are displayed on cell surfaces. This is carried out by Antigen-presenting cells (APCs), the most important of which are dendritic cells, B cells and macrophages. APCs can digest proteins they encounter and display peptide fragments from them on their surfaces for another immune cell to recognise.
There are several subtypes of T cells, these include: T helper cells, T memory cells and cytotoxic T cells. These cells have distinct functions and they work together in a complex network involving other immune cells to combat disease. They also help with long term defence against infection by development of immunological memory.