Complement- Regal

Question 1

What is complement?

Answer 1

A group of plasma proteins that acts as an auxiliary system in immunity on its own AND in conjunction with humoral immunity

Question 2

What are the specific functions of complement?

Answer 2

Lysis
Opsonization
Mediators of inflammation
Solubilization and clearance of immune complex/ apoptotic cells
*augments stimulation of the B cell

Question 3

What receptor augments stimulation of the B cell to increase humoral immune response?

Answer 3

CR2

Question 4

What begins the classical activation of complement?

Answer 4

Antibody binds antigen
C1q binds antibody
C1r self-activates and activates second C1r, both activate C1s

This complex is called C1 esterase (C1qr2s2)

Question 5

What components make up the C3 convertase in the classical pathway?

Answer 5

C4b2a

Question 6

What components make up the C3 convertase in the alternative pathway?

Answer 6

C3bBb

Question 7

***What proteins covalently bond to surfaces?

Answer 7

C4b and C3b

Question 8

What is the membrane attack complex? What molecules form the membrane attack complex?

Answer 8

Transmembrane channel that allows passage of ions and lysis of the cell

C5b+C6
+C7
+C8
+C9

Question 9

What even prevents the insertion and formation of MAC?

Answer 9

C5b-7 binding to S protein in the fluid phase

Question 10

What 3 things limit complement activation?

Answer 10

1. Short half life or the enzymes formed
2. Properties of non-activator surfaces
3. Inhibitors (fluid phase and membrane bound)

Question 11

What molecules are responsbile for the clearance of immune complexes and apoptotic cells?

Answer 11

C1qr2s2
C4 and C2
C3

Question 12

What molecules of complement are responsible for inflammation and T-cell regulation?

Answer 12

C3a and C5a

Question 13

What molecule is responsible for Opsoninsation and amplifying adaptive immunity

Answer 13

C3b

Question 14

What is factor H?

Answer 14

a fluid phase inhibitor of C3 convertase

If C3bBb is floating around, it binds to it and dissociates the Bb inactivating it

decay acceleration of the convertase

Can also bind C3b that is bound to membranes with sialic acid (our membranes)

Question 15

What is Factor I?

Answer 15

Factor I can degrade C3b that binds to membranes with sialic acid (need Factor H bound 1st as a cofactor)

Question 16

What will deficiencies of complement control proteins lead to? (in general)

Answer 16

uncontrolled activation of the complement system!

Lysis or..
Consumption of the complement components leading to the consequences of secondary complement deficiency (IC disease and infecitons)

Question 17

C1 InH deficiency

Answer 17

Normal prevents activation of C1 esterase

Deficiency = herediatary angioedema

Question 18

Deficiency in DAF

Answer 18

Increased susceptibility of erythrocytes to MAC-mediated lysis

Question 19

What is the role of CR1?

Answer 19

Transport of immune complexes by RBC

promotes immune adherence,binding of opsonized microbes to primate RBCs

Question 20

What is the role of CR2?

Answer 20

Augment stimulation of the B-cell (high affinity for EBV envelope protein)

Question 21

What are CR3 and CR4 involved in?

Answer 21

Found on monocytes, macrophages, PMN, NK cells, and T cells

involved in phagocytosis and cell adhesion
Binds immune complexes