MICR104A Complement System

Complement System

A defense mechanism that can be activated by both innate and acquired immune mechanisms. Consists of enzymatic pathways that cause specific proteins to bind covalently to the surface of invading microbes.

inactive

if you’re healthy, the complement system is ___

active

if you’re NOT healthy, the complement system is ___

numerically and letters

The proteins that form the complement system are labeled

liver, macrophages, neutrophils

sites of synthesis of Complement components

liver and neutrophils

C6 is from both of these 2 sites of synthesis

liver and macrophages

C3 and B is from both of these 2 sites of synthesis

Liver

C3, C6, C8, and B are found in this site of synthesis of Complement components

Macrophages

C2, C3, C4, C5, B, D, P, and U are found in this site of synthesis of Complement components

Neutrophils

C6 and C7 are found in this site of synthesis of Complement components

Classical, Alternative, Terminal, Control Proteins

the different pathways

Classical Pathway

C1q , C1r, C1s, C4, C2, C3 are found in this pathway

Alternative Pathway

D and B are found in this pathway

Terminal

C5, C6, C7, C8, C9 are ____ components

Control

C1-INH, C4BP, H, I, Ana INH, P, S are ___ proteins

Inhibitor

INH stands for

Classical, Terminal Classical, Alternative, Lectin

the different mechanisms of complement system

Classical Pathway

Activated by antibodies bound to antigens part of acquired immunity

C1

when this molecule is activated, it proteolytic cascade involving multiple other complement proteins

Classical Pathway

Generates inflammatory mediators, opsonin for phagocytosis of antigen and lytic complexes that destroy cells

C3 convertase

C4b2b is also called as

C5 convertase

C4b2b3b is also called as

a, b

when activated, it produces both _ and _

a

is usually released

b

usually binds

membrane attack complex (MAC)

C5b678 Complex Formation of a tubular structure called ___

MAC

inserts itself into a microbial cell membrane and effectively punches a hole in the invader

C5b67

C5bC6C7 is also written as

Alternative Pathway

Triggered by contact between microbial cell walls and complement components. Activated immediately when it comes into contact with blood thus a key component of innate immunity.

C3

most important complement protein synthesized by liver cells and macrophages and complement component of highest concentration in serum. Mediates inflammatory responses to infection as well as direct lysis of microbes

B factor

C3b is converted by this

C3 convertase

C3bBb is also called

Properdin

C3bBb is acted upon by this to bind to C3b

C5 convertase

C3bBb2b is also known as

Lectin Pathway

activated directly by microbial carbohydrates; also an innate defense mechanism

mannose-binding lectin (MBL)

most important lectin; can bind to the surface of bacteria, fungi, parasitic protozoa and viruses

mannose-binding lectin

MBL stands for

regulatory proteins

all of the activation pathways must be carefully regulated which is the role of this molecule

C1 inactivator (C1-INH)

is the most important regulator

C1 inactivator

C1-INH stands for

C1-INH

Controls the assembly of C4b2b by blocking the activities of active C1r and C1s

CD-55

Decay accelerating factor. Function is to protect normal body cells from complement attack.

Factor H & C4-binding protein

For acceleration of convertase degradation found in PLASMA

CD35 and CD46

For acceleration of convertase degradation found in CELL MEMBRANES

C4-binding protein

C4BP stands for

vitronectin, clusterin, CD59

these glycoproteins are For control of C56789 complex. They inhibit the C56789 insertion and C9 polymerization in cell membranes.

Protectin

CD59 is also known as

C3b

bound to a microbial surface is a very potent and effective opsonin

Chemotaxis

Major contributor to acute inflammation. Activation of the complement generates several potent chemotactic peptides

anaphylatoxins

C3a and C5a are

C3a and C5a

degranulate mast cells and stimulate platelets to release vasoactive molecules histamine and serotonin