Humoral Immune Response Flashcards Preview

CMBM 3 > Humoral Immune Response > Flashcards

Flashcards in Humoral Immune Response Deck (57)
1

List the 5 classes of immunoglobins.

IgM, IgG, IgA, IgE, IgD

2

What are the properties and functions of IgM?

-pentamer
***fixes complement
- first Ig made by fetus and B cells
-high avidity, low affinity
- present in colostrum and mother's milk (but does not cross the placenta)
- may or may not be produced during secondary immune response

3

What type of receptors on phagocytes binds IgM?

Fc receptors
-activates complement

4

What are the properties and functions of IgG?

- monomer
-major serum Ig (most abundant isotype in serum)
-major immunoglobulin of secondary immune response
***is transported across the placenta
- fixes the complement

5

What is the major immunoglobulin of the secondary immune response?

IgG

6

List the four sub-classes of IgG and how they are acquired.

Cg1
Cg2
Cg3
Cg4
the differences are different constant regions of the heavy chain

7

Why does IgG have a longer lasting immune response?

memory
affinity maturation

8

Which Ig can be transported across the placenta?

IgG

9

Which Ig's can fix the complement?

IgM
IgG

10

Which Ig's are opsonins?

IgM
IgG

11

What two forms does IgA exist?

IgA1 - monomeric
IgA2 - dimeric

12

Where is IgA found?

in serum and body secretions:
tears
saliva
gastric secretions
pulmonary secretions

13

What two Igs are present in colostrum and mother's milk?

IgA
IgM

14

What is the purpose of IgE? structure?

-Fc receptor binds to basophils & mast cells causing degranulation
-parasitic infections (Helminths)
structure: monomer

15

What is an important mediator in the granules?

histamine

16

What does histamine do?

increases vascular permeability which creates edema, hives

17

Where is IgD found? structure?

-on membrane of mature B cells (like IgM)
structure - monomer

18

What type of organisms activate the humoral response?

extracellular organisms

19

What are the phases of humoral response?

-B cell gets activated by one antigen
- B cell undergoes clonal expansion and differentiation
Two types (plasma & memory B cells)

20

Which chains on the B cell undergo rearrangement?

heavy chains

21

Which chain undergoes class switching?

heavy

22

Which chromosome is the heavy chain found? light chain?

heavy - chromosome 14
Light
- chromosome 2 (kappa)
- chromosome 22 (lamda)

23

How do we change immunoglobulins?

triggers which cause class switching: changing of the constant regions

24

Distinguish between primary and secondary antibody responses.

Primary
- 5-10 day lag
- peak response is smaller
- IgM> IgG
- lower affinity

Secondary
- 1-3 day lag
- peak response is larger
- IgG (IgA, IgE if heavy chain isotype switching)
- higher affinity

25

IgG has a higher (avidity/affinity)?

affinity

26

IgM has a higher (avidity/affinity)?

avidity

27

Which segment gets deleted in class switching?

c segments

28

Which B cells are T-dependent?

follicular B cells

29

Which B cells are T-independent?

Marginal zone B cells
B1 B cells

30

Which B cells are able to class switch?

T-dependent follicular b cells

31

T-independent B cells are mainly what type of Ig?

IgM
short lived

32

Where will you find the CD5 marker?

B-1 B cell; not specific

33

T dependent activation is due to a CD40 ligand binding to a B cell's ___.

CD40

34

What type of antigen is present when class switching is activated?

protein antigens

35

What type of antigen is present in T-independent activation?

polysaccharides, nucleic acid, lipids

36

In what part of the spleen will B cells be?

white pulp

37

After a splenectomy, an individual will be susceptible to which organism?

Strep pneumo

38

What is Hyper IgM syndrome?

- can only produce IgM
-results from mutations affecting class switching

39

What recognition is required between a Tcell and Bcell for class switching?

Cd40L - CD40
CD28/B7 (CD 88)
Th1 releases cytokines IL4 / IL4R ----clonal expansion
IL5 ---differentiation

40

What would you expect if a Tcell did not have CD40 ligand?

- repeated chronic infections
-elevated IgM but no class switching
- no secondary response available

41

What happens when FasL is activated?

cell undergoes apoptosis
-important if there was a defective FasL (lymphoproliferative syndrome)

42

What are the three pathways of the complement cascade?

Classical Pathway (antigen antibody complex)
MB-Lectin Pathway (lectin binding on pathogen surface, )
Alternative Pathway (polysaccharides found on bacterial cell wall)

43

How are the complement cascades different?

activation is different

44

Where are complements produced?

liver; problems with liver can give you complement problems

45

Which complement protein has 3 subunits?

C1q
C1r
C1s

46

Describe the process of the classical pathway.

1. Once antibody is bound to antigen, a receptor will bind to C1q. Once complex is bound to C1q, it will activate C1r and then C1s.
2. Activates C2 and C4. Cleaves subunits C2a, C2b, C4a, C4b
3. C4b and C2b will make C3 convertase.
4. C3 is cleaved. C3b, C4b, C2b make C5 convertase.
5. C5 cleaved and then C6-9 are added to make MAC complex.

47

Describe the process of the lectin pathway.

1. Mannose binding lectin causes C4 and C2 cleavage.
2. C4b and C2b will make C3 convertase.
3. C3 is cleaved. C3b, C4b and C2b make C5 convertase.
4. C5 cleaved and then C6-9 added to make the MAC complex.

48

Which components of the complement pathways are inflammatory mediators?

C3a
C5a

49

Describe the process of the alternative pathway.

1. Activated by non-protein antigens. in the presence of Factor D, Factor B will be activated
2. C3b and Bb will make C3 Convertase
2. C3 will be cleaved
3. C3b, Bb, and C3b will make C5 convertase
4. C5 cleaved and then C6-9 added to make a MAC complex

50

What is the function of the complement?

-phagocytosis and killing of microbe
-osmotic lysis of microbe
-destruction of microbes by leukocytes

51

What is the biological function of C2b?

-prokinin
-associate with edema & cough

52

What is the biological function of C3a?

anaphylotoxin

53

What is the biological function of C3b or C4b?

opsonin - promotes phagocytosis

54

Where are CR1 found?

B cells
phagocytes
RBS
follicular dendritic cells

55

Where are CR2 found?

Bcells
epithelial

56

Where are CR3 and CR4 found?

phagocytes

57

How do bacteria evade the humoral immune response?

- form different antigens
- inhibition of complement activation
- resistance to phagocytosis