Complement System

Question 1

innate immune system

Answer 1

The component of the immune system in animals that is genetically determined and is nonspecific, as distinguished from the adaptive immune system

Question 2

Elements of the innate system include (6)

Answer 2

mucous secretions, complement proteins, and certain white blood cells, especially neutrophils, macrophages, and dendritic cells

Question 3

adaptive immune system

Answer 3

The component of the vertebrate immune system involving lymphocytes (B cells and T cells) containing a small number of genetically encoded proteins that combine to produce an enormous variety of proteins capable of recognizing and deactivating specific antigens

Question 4

two major functions of the complement system

Answer 4

alters the membrane of pathogens and cellular debris
enhance the inflammatory response via release of anaphylatoxins that promote cell activation (e.g. mast cell degranulation) or migration to an inflammatory site (chemotaxis)

Question 5

opsonization promotes removal of particles via

Answer 5

complement receptors on host cells

Question 6

Opsonization also leads to assembly of the

Answer 6

membrane attack complex on pathogens and subsequent lysis

Question 7

The complement system becomes activated on a target, such as (3)

Answer 7

apoptotic cells, tissue debris, or pathogens

Question 8

This occurs by at least three mechanisms that are independent of a prior adaptive immune response :

Answer 8

(i) natural, spontaneous turnover (i.e. ‘tick over’) of C3 engages the alternative pathway (AP)
(ii) binding to the target of naturally occurring antibodies (Abs) engages the classical pathway (CP)
(iii) binding of lectins to carbohydrates on the target engages the lectin pathway (LP)

Question 9

In adaptive immunity, natural Abs are replaced by

Answer 9

specific Abs

Question 10

complement triggers (3)

Answer 10

phagocytosis
inflammation
membrane attack

Question 11

phagocytosis by

Answer 11

opsonizing agents

Question 12

what has the most important ozonizing activity?

Answer 12

C3b

Question 13

inflammation by

Answer 13

chemotactically attracting macrophages and neutrophils (anaphylatoxins C3a and C5a)

Question 14

membrane attack by

Answer 14

rupturing the cell wall of bacteria

Question 15

Inflammation is a local response to cellular injury that is marked by (5)

Answer 15

capillary dilatation, leukocytic infiltration, redness, heat, and pain

Question 16

inflammation serves as a mechanism initiating the elimination of

Answer 16

noxious agents and of damaged tissue

Question 17

Swelling is produced by the release of serum into the tissues (wheal), and redness of the skin, resulting from the dilation of

Answer 17

blood vessels (flare)

Question 18

The Classic Pathway is triggered by activation of the

Answer 18

C1-complex

Question 19

The Mannose-Binding Lectin pathway is homologous to the — —, but uses the —; mannose-binding lectin (MBL), and ficolin, instead of C1q

Answer 19

classical pathway

opsonins

Question 20

The Alternative pathway is continuously activated at a low level, as a result of spontaneous

Answer 20

C3 hydrolysis

Question 21

spontaneous C3 hydrolysis due to the breakdown of the

Answer 21

internal thioester bond

Question 22

C3 is mildly unstable in

Answer 22

aqueous environment

Question 23

The alternative pathway does not rely on — — — like the other pathways

Answer 23

pathogen-binding antibodies

Question 24

in the classical pathway of complement, there is cleavage of (3)

Answer 24

C2
C4
C3

Question 25

C1, is a complex of (3)

Answer 25

C1q, C1r, and C1s

Question 26

C1q is composed of

Answer 26

six identical subunits with globular heads and long collagen-like tails. The tails combine to bind to two molecules each of C1r and C1s, forming the C1 complex C1q:C1r2:C1s2. The heads can bind to the constant regions of immunoglobulin molecules or directly to the pathogen surface, causing a conformational change in C1r, which then cleaves and activates the C1s zymogen.

Question 27

diseases which involve complement in their mechanism (7)

Answer 27

• Paroxysmal nocturnal hemoglobinurina
• Atypical Hemolytic uremic syndrome (aHUS)
• Hereditary angioedema
• Autoimmune diseases (Systemic lupus erthrymetosis, dermatomyositis, rheumatoid arthritis)
• Age-related macular degeneration
• Primary immune deficiency syndrome
• Mannose-binding lectin deficiency

Question 28

Paroxysmal nocturnal hemoglobinurina

Answer 28

Acquired disorder that results in premature death and impaired production of blood cells

Question 29

Paroxysmal nocturnal hemoglobinurina effects (3)

Answer 29

RBCs, leukocytes and platelets

Question 30

how does Paroxysmal nocturnal hemoglobinurina effect by gender

Answer 30

affects both sexes equally,

Question 31

when is Paroxysmal nocturnal hemoglobinurina usually diagnosed

Answer 31

usually diagnosed in young adulthood

Question 32

Paroxysmal nocturnal hemoglobinurina is a deficiency of the

Answer 32

DAF protein

Question 33

Atypical hemolytic uremic syndrome results from

Answer 33

chronic uncontrolled activation of the complement system

Question 34

in Atypical hemolytic uremic syndrome, multiple blood clots form throughout body in small blood vessels which can lead to (4)

Answer 34

stroke
heart attack
kidney failure
death

Question 35

Atypical hemolytic uremic syndrome is due to mutations in (3)

Answer 35

factor H
factor I
membrane cofactor protein

Question 36

the most common functional defect in atypical hemolytic uraemic syndrome and age-related macular degeneration is

Answer 36

reduced cofactor activity (MCP or factor H) for C3b

Question 37

Hereditary Angioedema is recurrent attacks of

Answer 37

severe swelling

Question 38

types 1 and 2 Hereditary Angioedema

Answer 38

mutations in the gene that makes the C1 inhibitor

Question 39

type 1 is a deficiency of

Answer 39

C1

Question 40

type 2 is an atypical

Answer 40

C1 protein that is less capable of suppressing activation of the complement system

Question 41

type 3 Hereditary Angioedema is often due to mutations in

Answer 41

factor XII gene