[IMSE LEC, 2S] Complement System

Question 1

Group of proteins synthesized in mononuclear phagocytes, fibroblasts, endothelial cells, and liver cells

Answer 1

Complement (C’)

Question 2

Complement is a group of proteins synthesized in _____, _____, _____, and _____.

Answer 2

Mononuclear Phagocytes
Fibroblasts
Endothelial Cells
Liver Cells

Question 3

Complement are ________ (soluble/insoluble) mediator of the immune system

Answer 3

SOLUBLE Mediator

Mediator because they induce immune response

Question 4

4 Functions of Complement (C’)

Answer 4

1. Disruption of microbial cell walls
2. Inflammatory mediation
3. Regulation of phagocytic activity
4. Metabolism of immune complex

*In inflammatory mediation, complement releases anaphylatoxins = molecules that induce inflammatory response

Question 5

_______ refers to a series of serum proteins that are normally present and contribute to inflammation

Answer 5

Complement

Question 6

The major functions of complement are: ______, ______, and _____.

Answer 6

1. Opsonization
2. Chemotaxis
3. Lysis of cells

Question 7

Complement protein _____ is a portent anaphylatoxin and chemotaxin.

Answer 7

C5a

Question 8

Complement protein _____ increases vascular permeability and to attract WBCs to the site of inflammation.

Answer 8

C5a

Question 9

T/F

Complement activation can also have PROinflammatory effects

Answer 9

TRUE

because of its ability to increase vascular permeability, recruit monocytes and neutrophils to the area of antigen concentration, and trigger secretion of immunoregulatory molecules that amplify the immune response.

Question 10

Major Activators and their Distinct Pathway:

1. IgM or IgG (minor: CRP): _____________
2. Lipopolysaccharide: __________
3. Mannose-containing residues of glycoproteins: ___________

Answer 10

IgM or IgG: Classical C’ Pathway

Lipopolysaccharide: Alternative C’ Pathway

Mannose-containing residues of glycoproteins: Mannan-binding Lectin Pathway or Lectin Pathway

Question 11

The outcome of these activators are the same: create _______, increase _______ activity, and ________

Answer 11

Create anaphylatoxin,
increase phagocytic activity,
cause cell lysis

Question 12

The major activator of the classical pathway is ________-

Answer 12

Antigen-antibody complexes

The presence of this antibody which are bound to the surface of the pathogen will cause the response of the classical complement pathway to induce its effect.

Question 13

The minor activator of the classical pathway is ________

Answer 13

CRP (C-Reactive Protein)

It is a component of inflammatory response; an acute phase reactant that can activate classical pathway

Question 14

The major activator for the Alternative Pathway is ________

Answer 14

Lipopolysaccharide

Found in the surface of pathogen

Question 15

The major activator for Lectin Pathway is _________

Answer 15

Mannose-containing residues of glycoproteins

AKA “terminal mannose residues”

These are found in the surface of the pathogen that can activate the pathway. Expressed by Gram POSITIVE or Gram Negative bacterials and yeast particles

Gr+ = S. Aureus
Gr- = E. coli, Klebsiella

Question 16

9 Proteins involved in the Classical pathway

Answer 16

C1qrs
C2
C3
C4
C5
C6
C7
C8
C9

** C1 has different subunits (C1q, C1r, C1s)

Question 17

3 unique proteins involved in the Alternative Pathway

Answer 17

Factor B
Factor D
Properdin

• Alternative Pathway was called “Properdin Pathway”

Question 18

4 proteins involved in MBL Pathway

Answer 18

MBL,
MASP-1
MASP-2 (major),
MASP-3 (minor)