alternative pathway
Quick Summary
The alternative pathway is one of three ways the complement system in immunology is activated. This system is composed of proteins that help the body fight off infections by causing lysis of foreign cells, enhancing phagocytosis, and promoting inflammation.1
Unlike the classical pathway, which requires antibodies, the alternative pathway is triggered by molecules on the surface of invading microorganisms. This makes it a crucial part of the body's initial, non-specific defense against pathogens. The activation of this pathway leads to the activation of a key protein called C3, which then helps eliminate the invader by either directly damaging its membrane or by marking it for destruction by white blood cells.1
Ask Britannica AI about this topic
Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.
complement…the lectin pathway, and the alternative pathway (or properdin system). A different type of signal activates each pathway. The classical pathway is triggered by groups of antibodies bound to the surfaces of a microorganism, while the lectin pathway is spurred into action by mannan-binding lectin, a constituent of serum that…
Read More…the lectin pathway, and the alternative pathway (or properdin system). A different type of signal activates each pathway. The classical pathway is triggered by groups of antibodies bound to the surfaces of a microorganism, while the lectin pathway is spurred into action by mannan-binding lectin, a constituent of serum that…
Read More
immune systemActivation of the complement system…by antigen-antibody complexes; and the alternative pathway, which is triggered by other means, including invading pathogens or tumor cells. (The term alternative is something of a misnomer because this pathway almost certainly evolved before the classical pathway. The terminology reflects the order of discovery, not the evolutionary age of the…
Read More…by antigen-antibody complexes; and the alternative pathway, which is triggered by other means, including invading pathogens or tumor cells. (The term alternative is something of a misnomer because this pathway almost certainly evolved before the classical pathway. The terminology reflects the order of discovery, not the evolutionary age of the…
Read More