What are the components of the adaptive immune system? What functions do they perform?

The adaptive immune system is a highly specialized defense mechanism that provides immunity against a wide range of pathogens. It is characterized by its ability to recognize and remember specific antigens, allowing a stronger and more targeted response upon subsequent exposures. The two main components of the adaptive immune system are B cells and T cells.

B cells are a type of white blood cell that plays a critical role in the humoral immune response. They are responsible for producing and secreting antibodies, which are proteins that can specifically recognize and neutralize foreign substances such as bacteria and viruses. Upon activation by an antigen, B cells mature into plasma cells, which are the cells responsible for producing large amounts of antibodies, and memory B cells, which provide long-term immunity by remembering the specific pathogens that have been encountered.

T cells are also a type of white blood cell, with a central role in cell-mediated immunity. T cells can be subdivided into different subsets, such as helper T cells (CD4+), cytotoxic T cells (CD8+), and regulatory T cells (Treg), among others. Helper T cells provide support for other cells in the immune response, such as stimulating B cells to produce antibodies and activating cytotoxic T cells. They primarily function by releasing signaling molecules called cytokines. Cytotoxic T cells have the ability to recognize and directly destroy infected cells and cancer cells. They achieve this through the release of molecules like perforin and granzymes, which can induce apoptosis in the target cells. Regulatory T cells help to maintain immune tolerance by suppressing the immune response to self-antigens and preventing autoimmune diseases.

The adaptive immune system consists of two main components, B cells and T cells, which provide humoral and cell-mediated immunity, respectively. B cells produce antibodies that can specifically neutralize foreign substances, while T cells can provide support for other immune cells, directly destroy infected cells, and help maintain immune tolerance. Both components work together to generate a highly specific and long-lasting immune response against pathogens.