8 B Cell Mediated Immunity I Flashcards Preview

Immunology Test 1 > 8 B Cell Mediated Immunity I > Flashcards

Flashcards in 8 B Cell Mediated Immunity I Deck (36):
1

What is the signal transduction unit of the B cell receptor (BCR)?

IgAlpha and IgBeta complex crosslinking

2

What is the co-recptor for the BCR?

Complement Receptor 2 (CR2) binding to C3b

3

What signals are required for B cell activation?

BCR
CR2
T cell help

4

What is the difference between Thymus Dependent and Thymus Independent Antigens?

Dependent Antigens need Costimulation by Helper T cell to activate B cells

5

Do B cells and T cells that are in the Germinal center reaction have to have the same antigen to activate them?

No, they can be activated by different antigens

6

What two ways do TI antigens overcome the need for T cell help?

1. TI-1 Antigens:
Stimulate via different route:
Engage BCRs as well as PRRs
these are known as "mitogens"
2. TI-2 Antigens:
Heavily crosslink BCRs
these usually respond to cell wall parts

7

What do B1 cells respond to?

Cell wall polysaccarides

8

What do mitogens activate?

Both BCRs and PRRs to activate B cells without T cell costimulation

9

What are Infants and Toddlers unable to make that limit their response to cell wall antigens?

B1 B cells

10

What type of activation of B cells do high concentration of TI-1 antigens illicit?

Polyclonal (not monoclonal) expansion and non-specific antibody response

11

What type of activation of B cells do low concentrtion of TI-1 antigens illicit?

Antigen specific response, usually via IgM production

12

What are the limitations of Thymus Independent (TI) responses?

Nonspecific
No class switching
No Memory (so each response will have to start over)
B cell response never changes

13

What type of antigen can infants and toddlers not respond to?

TI-2 antigens
usually cell wall components, crosslink BCRs

14

Where do germinal center reactions occur?

Lymphoid follicles of secondary lymph (nodes)

15

What happens in the germinal center?

somatic hypermutation
class switching
cytokine production

16

What is an overview of B cell activation in the germinal center reaction?

1. Antigen-specific B cells enter the T cell zones
2. B cells interact with antigen-activated Th2 cells to form a primary locus
3. Germinal center reaction (positive selection and monoclonal expansion)
4. Plasma (early) and Memory (late) Cell production

17

What are Follicular Dendritic Cells?

Use complement and antibodies to pick up antigens to present
Do not use MHC class II
Antigens
Not APCs
Like a buffet of antigens

18

What does IL 5 induce in class switching in B cells?

IgA class switching

19

What does IL 4 induce in class switching in B cells?

IgE class switching

20

What is virtually the only thing a Plasma Cell is used for?

Antibody production 30-60 days post infection

21

What antibodies are found in the blood?

IgG
IgM
IgA

22

What antibodies are found in the mucus?

IgA

23

Where is IgE found?

Mast cell FceRI receptor in skin, BALT, GALT

24

How do multimeric Igs enter the tissues from blood?

Poly-Ig receptor and transcytosis

25

How do IgGs enter the tissues from blood?

Brambell receptor and transcytosis

26

How do IgGs enter the placenta?

Brambell receptor (FcRn)

27

What Ig is associated with crossing the placenta?

IgG

28

What are examples of passive transfer of immunity?

Injection of antibodies
Maternal Ig's via breast milk and placental barrier on Brambell receptors

29

What fetal Ig is at the same concentration as maternal?

IgG

30

What Ig is secreted in breast milk?

IgA

31

How does the Ig of breast milk enter the tissues?

Poly-Ig Receptor

32

When does infant IgM kick in?

5-9 months

33

When do IgG and IgA kick in?

1 year to high levels

34

What Fc Receptors were highlighted in lecture?

FcEpsilon Receptor: Binds IgE in mast cells
FcyReceptor III: Bind IgG1
Induce NK cells and APCs

35

What do Ig's need to be active? Exception?

Antibody needs to be bound
FcEpsilon is the exception (binds IgE free in blood to highjack for Mast cell use as antigen receptors)

36

What WBC targets parasites coated with IgE?

Eosinophils