Komplementkerfið

Komplementkerfið, also known as the Complement System, is a crucial part of the innate immune system in vertebrates. Its primary function is to enhance the ability of the adaptive immune system to clear pathogens by marking them for destruction. The system is composed of a series of proteins that work together in a cascade-like manner to amplify and regulate the immune response.

The Complement System can be activated through three main pathways: the classical pathway, the alternative pathway, and the lectin pathway. Each pathway initiates a series of enzymatic reactions that lead to the formation of the membrane attack complex (MAC), which creates pores in the membrane of the pathogen, causing its lysis.

The classical pathway is activated by the binding of antibodies to the surface of a pathogen. The alternative pathway is constantly active and can be triggered by the presence of foreign particles, such as bacteria or viruses. The lectin pathway is activated by the binding of mannose-binding lectin to carbohydrates on the surface of pathogens.

Once activated, the Complement System produces a variety of products, including anaphylatoxins, which can cause inflammation, and opsonins, which enhance phagocytosis. The MAC is the most potent component of the Complement System, as it directly lyses the membrane of the pathogen.

The Complement System plays a vital role in host defense, particularly against encapsulated bacteria and certain viruses. It also has a regulatory function, helping to limit the immune response and prevent tissue damage. Dysfunction of the Complement System has been linked to various diseases, including autoimmune disorders and certain types of infections.