2.4.9 B-cell immunity

Question 1

_____ is the important IL in the activation of B-cells (which now proliferate) and IL-____(2) play a role in differentiation of B-cells to plasma cells

Answer 1

IL4
-IL6, IL10

Question 2

what are some major differences between resting B cell and plasma cell? (IgG, MHCII, Ig secretion)

Answer 2

Resting B:
- YES surface Ig
-YES surface MHCII
- NO high rate Ig secretion

Plasma cell
- NO surface Ig
-NO surface MHCII
- YES high rate Ig secretion

Question 3

Naive T-cell recognizes _____ antigen and searches for specific antigen presented by ______ before it can start proliferating.

Naive B-cell recognizes _____ antigen and searches for specific antigen presented by ______ before it can start proliferating.

Answer 3

1. Processed antigen, dendritic cell (hematopoietic origin)
2. naive part of antigen, FDC (not hematopoietic origin)

Question 4

does FDC process antigen?

Answer 4

NO

Question 5

_____ covers virus particles due to complement activation, CR1 on FDC can now bind the virus and retain it at the cells surface.

Answer 5

C3b

Question 6

C3b can be cleaved by ____ into ____ which can then bind to CR2 on FDC

Answer 6

Factor 1 cleavage
C3d

Question 7

In the lymph node, the B-cell and TfH CD4+ T-cell will interact. Where can they go?

Answer 7

1. medullar cords and B-cells differentiate into plasma cells
2. back to primary follicle where the B-cells actively divide to form a germinal center

Question 8

_______ in the __ region of the antibody molecule happens in the germinal center and results in Antibodies with high affinity

Answer 8

somatic hypermutation
V region

Question 9

B-cells with high affinity ________
B-cells with low affinity __________

Answer 9

1. can interact with antigen on FDC and T-helper at the same time, then differentiate into plasma cells
2. die by apoptosis

Question 10

Apoptotic cells engulfed by macrophages in the Germinal center are called _____

Answer 10

tingible body macrophages

Question 11

explain the difference of B-cells that mature under the influence of IL10 Tfh cells vs IL4 Tfh Cells

Answer 11

• IL10 secreting Tfh
  causes b-cell to differentiate into plasma cells that make antibodies

-IL4 secreting Tfh
causes B-cells to differentiate into memory B-cells which prevents future infections

Question 12

what must the antigen be like for there to be T-independent response?

Answer 12

antigen consists of repetitive epitopes (lipopolysaccharides, capsular polysaccharides)

Question 13

Is there usually class switching in T-independent response?

Answer 13

NO, mainly only IgM associated with B1 cells

Question 14

why do T-independent responses only have IgM ?

Answer 14

class-switching requires T-cell help

Question 15

the majority of antigens we encounter are _______, which results in _____ involving _____ cells

Answer 15

T-dependent antigens
class switching
B2 cells

Question 16

In T-dependent responses what effect can these different cytokines have?
1. IL4
2. TGF-Beta

Answer 16

1. induces IgE production
2. class switching to IgA

Question 17

IgM usually exists as a ______ and is found in the _______ defending against ______

Answer 17

• pentamer
• blood
• bloodborne pathogens

Question 18

what are the polymeric antibodies that have J chains?

Answer 18

IgA and IgM

Question 19

_____ is the major antibody class in blood and is the only class to cross the placenta

Answer 19

IgG

Question 20

what are the 2 different IgG subclasses we need to know?

Answer 20

IgG1 - proteins - induce IgG1 response
IgG2 - polysaccharides - induce IgG2 response

Question 21

what is the half life of IgG?

Answer 21

1 month

Question 22

_______ responds to protein antigens while ______ responds to carbohydrate antigens

Answer 22

IgG1
IgG2

Question 23

what happens in an in utero infection?

Answer 23

fetus can make IgM and IgG

Question 24

there is a ______ receptor on the endothelial cell that binds to IgG that can then bring it to the extracellular space

Answer 24

FcRn

Question 25

what is the IgD function?

Answer 25

there is none we know of

Question 26

what is the IgE funtion?

Answer 26

associated with allergic reactions and important in parasitic infections

Question 27

IgE can attach to ________ and also activate ______

Answer 27

-mast cells/basophils -eosinophils

Question 28

IgE helps _____ bind to parasite with _____ which then kills the parasite

Answer 28

eosinophils, Fc sigma RI

Question 29

_____ is the major antibody class in external secretions. it also protects mucosal surfaces

Answer 29

IgA

Question 30

IgA produced by plasma cells are a ______

Answer 30

dimer with J chain

Question 31

IgA in blood are a ______

Answer 31

monomer without J chain

Question 32

there is a ________ expressed on epithelial cells for IgA to be released out

Answer 32

Ig / J chain receptor

Question 33

what happens in peoples bodies who cant make IgA?

Answer 33

many more IgMs because that is the other Ig that has J chain

Question 34

The secretory component (SC) plays a large role in _____

Answer 34

active transport of IgA out

Question 35

what Ig is found in saliva? in gingival exudate?

Answer 35

-S-IgA -IgG

Question 36

what is the ratio of IgA to IgG in saliva?

Answer 36

19:1

Question 37

do patients with periodontitis have more IgG or IgA?

Answer 37

IgG

Question 38

_______ can degrade S-IgA1 and make it non-functional

Answer 38

IgA protease (oral pathogens can produce this)

Question 39

which Igs can do these: 1. Neutralization 2. Opsonization 3. Sensitization for killing by NK 4. Sensitization of mast cells 5. activate complement system

Answer 39

1. G, A 2. G 3. G 4. E 5. M,G

Question 40

________ clump bacteria and enhance their removal (usually IgM)

Answer 40

agglutinins

Question 41

______ enhance phagocytosis ; antibody coated microbes attach to Fc receptor on phagocytic cells (IgG most often)

Answer 41

opsonins

Question 42

what else can be involved in opsonization? (its part of complement activation)

Answer 42

C3b

Question 43

what two things can both be activated and result in an enhanced ability to do phagocytosis?

Answer 43

Fc receptor and C3b receptor

Question 44

________ antibodies are Abs that neutralize viruses or bacterial toxins (IgG or IgA)

Answer 44

neutralizing antibodies

Question 45

what are 2 examples of actions of neutralizing antibodies?

Answer 45

- antibody protects cell by blocking binding of a toxin - antibody blocks binding to virus receptor and an block fusion event

Question 46

_____ cause disruption of cell membrane and can activate complement system (IgG and IgM)

Answer 46

Lysins

Question 47

______ antibodies prevent attachment of microbes to cells or hard surfaces (ex: S-IgA prevents bacteria from adhering to teeth)

Answer 47

Anti-adherance antibodies

Question 48

______ plays a role in bringing IgG across the placenta and from blood --> tissue

Answer 48

FCRN

Question 49

what is antibody dependent cell toxicity? (ADCC)

Answer 49

1. antibody binds antigens 2. Fc receptors on NK cells recognize bound antibody 3. cross-linking of Fc-gamma-R3 - NK kills the target cell

Question 50

In ADCC what is the other name for Fc-gamma-R3

Answer 50

CD16

Question 51

_______ is used as part of targeted therapy in treating patients with B-cell leukemias and lymphomas

Answer 51

anti-CD20

Question 52

______ tightly adheres to IgE antibody. this receptor is expressed by mast cells, basophils, and activated eosinophils

Answer 52

Fc-epsilon-R1

Question 53

does IgE in blood have a long or short half life?

Answer 53

SHORT

Question 54

How do RBC facilitate removal of immune complexes from circulation?

Answer 54

1. antigen/antibody complex forms & activates complement 2. immune complex coated with C3b 3. CR1 (Fc-gamma-R1) on RBC binds C3b tagged immune complex 4. RBC goes to liver/spleen and organs strip immune complexes and ingest/destroy them