The adaptive immune system, also known as acquired or specific immunity, is a highly sophisticated defense mechanism found in vertebrates, including humans. It is one of the two main components of the immune system, along with the innate immune system. The adaptive immune system is responsible for recognizing and eliminating specific pathogens or foreign substances that enter the body.
What sets the adaptive immune system apart from the innate immune system is its ability to remember and develop targeted responses to particular pathogens. This dynamic system maintains a library of specialized white blood cells called lymphocytes, including B cells and T cells. These cells possess receptors that are designed to recognize unique molecules, known as antigens, which are present on the surface of pathogens or foreign substances.
When the adaptive immune system encounters an antigen that it has previously recognized, it activates a cascade of responses to destroy the invader. B cells produce antibodies, proteins that bind to the specific antigen and mark it for destruction, while T cells directly attack and kill the infected cells.
The adaptive immune system also exhibits immunological memory. Once exposed to an antigen, immune cells retain the ability to recognize and mount a quicker and more robust response upon subsequent encounters with the same pathogen. This memory allows for long-term protection against recurring infections.
Overall, the adaptive immune system is a complex network of cells and molecules that plays a crucial role in protecting the body against harmful pathogens, and its ability to adapt and remember is key in providing immunity to a wide range of infectious diseases.
