SI Complement system

How do microbes evade the complement system?

By their capsules, which prevent complement activation. Inactivation of the complement system prevent opsonization. Inhibition of MAC (membrane attack complex). Enzymes can inhibit your MAC proteins (protease) which inhibit action of complement protein

What is an interferon

Class of similar antiviral protein produced by certain animal cells, such as lymphocytes and macrophages after viral stimulation. Interferes with viral multiplication

What is the complement system?

Defense system consisting of over 30 proteins produced by the liver and circulating blood serums. -"Complement" cells of the immune system. -Cascade activated by pathogen directly or by an antibody-antigen reaction -Non-adaptable but brought into action by adaptive immune system -Together these proteins destroy microbes by enhanced phagocytosis, inflammation, and cytolysis

What are the outcomes of compliment system activation?

Opsonization, Inflammation, Cytolysis

What is the mechanism of action of interferons?

Tells neighbor cell to synthesize antiviral protein. Interferons are host specific

What is Cytolysis?

bursting of microbe due to inflow of extracellular fluid through the transmembrane channel by the membrane attack complex (C5b, C6, C7, C8 and fragments of C9)

What is Opsonization?

enhancement of phagocytosis by coating of C3b protein

What is inflammation?

increase of blood vessel permeability and chemotactic attraction of phagocytes cause by C3a and C5a causing mast cells to release histamine (C5a attracts phagocytes)

Example of Complement system

membrane attack complex which forms to cause cytolysis from C5-C8 with fragment of C9 to form channel,coating of C3b triggers chemotaxis to begin enhanced phagocytosis by opsonization, C3a and C5a mast cells triggers secretion of prostaglandin histamines for inflammation