3 Humoral Immunity Part 1

Question 1

Alright I know some cards are long…

Answer 1

But I spent a lot of time integrating concepts scattered across different slides to make comparisons simple, so that is why.

Question 2

T/F Only a few B cells are normally present in the periphery that can bind any 1 antigen?

Answer 2

True

Question 3

T/F a mature B cell requires a costimulatory signal in addition to BCR engagement when it finds its antigen?

Answer 3

True

Question 4

What molecules are expressed on B-1a cells?

Answer 4

IgM high
IgD lo
CD11b
CD5

Question 5

What molecules are expressed on B-1b cells?

Answer 5

IgM high
IgD lo
CD11b

Question 6

What molecules are expressed on B-2 MZ (marginal zone) cells? Where are these cells found?

Answer 6

IgM high
IgD lo
-Spleen white pulp marginal zones

Question 7

What molecules are expressed on B-2 FO (follicular) cells? Where are these cells found?

Answer 7

IgM lo
IgD high
CD23
-All peripheral lymphoid organs, esp follicles of spleen and lymph node

Question 8

Where are both types of B-1 cells typically found?

Answer 8

lung pleura and peritoneal cavity (just outside GALT & BALT) and tiny bit in spleen, lymph nodes

Question 9

What kind of antigens do both types of B-1 cells recognize?

Answer 9

Macromolecules usually produced by microbes esp in cell walls:

• Polysaccharides
• Phospholipids
• Self-antigens like phospholipid/cell membrane proteins

Question 10

What is the reason for why B-1 cells only recognize certain types of antigens?

Answer 10

B-1 cells contain only a restricted set of the V(heavy chain) gene segments

Question 11

What types of B cell is known to be a constant source of “natural” IgM antibodies? Which are an immediate source of IgM’s (within hours) of specific IgM’s? What do these IgM’s do?

Answer 11

• B-1
• MZ B-2’s
• Pool of ready-to-use antibodies for early stages of infection

Question 12

IgM’s are biased to attack what?

Answer 12

Microbial products like cell walls (like the B-1 cells that produced them!)

Question 13

Where are B-2 cells produced? Where do they mature?

Answer 13

• In fetal liver and in bone marrow

- In spleen

Question 14

Which B cell type is responsible for young childrens’ susceptibility to encapsulated bacteria? What do their antibodies target?

Answer 14

• MZ B-2 cells (these don’t appear until AFTER birth)

- Microbial products (like B-1 cells)

Question 15

Which B cell types are abundant? Which are few?

Answer 15

Very abundant: FO B’2s
Low abundance: All B-1’s
Few: MZ B-2’s

Question 16

T/F The B-1 progenitor and B-2 progenitor cell are the same?

Answer 16

False (Hematopoietic Stem Cell is their earliest common progenitor)

Question 17

When in our lifetime are B’1s produced? How about FO B-2’s and MZ B-2’s?

Answer 17

• Mostly fetus/neonate, but persist and self-renew in adult. Also a few are still made from scratch in adult.
• FO B-2’s during fetus/neonate, then generated continuously throughout adulthood
• MZ B-2’s begin production AFTER birth

Question 18

Of the 4 kinds of B cell, which produces highly diverse antibodies?

Answer 18

FO

Question 19

Which B cell type is responsible for young childrens’ susceptibility to encapsulated bacteria? What do their antibodies target?

Answer 19

• MZ B-2 cells (these don’t appear for a while after birth)

- Microbial products (like B-1 cells)

Question 20

Each mature B cell (in the periphery) expresses how many types of antibody?

Answer 20

1 (and only 1 antigen specificity)

Question 21

What are the components of the BCR?

Answer 21

• • Dif than T cells:
• Antibody (no signaling)
• CD79a, CD79b (a.k.a. Ig alpha/beta) are the signaling link
• Co-receptors CD 81, 19, 21 modify/amplify response

Question 22

What happens to activated FO B cells?

Answer 22

Migrate toward border of the CD 4 T cell zones in lymph node

Question 23

MZ B’s main function is?

Answer 23

Respond to blood-borne antigens (including those in the red pulp)

Question 24

What is B cell signal 1? What happens w/ this signal alone?

Answer 24

• Engagement of multiple BCR’s

- Death/anergy

Question 25

Name the characteristics of TI (thymus-independent in mice) responses?

Answer 25

• Low magnitude
• Low affinity Ab’s
• No memory
• Early phase and short lived
• Don’t need CD4’s, so no germinal center response
• IgM antibodies (with some IgG and IgA and limited class switching)
• Induced by repetitive structural complexes that activate multiple BCR’s

Question 26

What is B cell signal 3?

Answer 26

Cytokines (from CD4’s or activated innate cells)

Question 27

What safeguards against B cells going rogue and producing antibodies?

Answer 27

Signal 2 and 3

Question 28

What is special about Type 1 TI antigens? What is our example?

Answer 28

• activate PRR’s like TLR (signal 2)

- LPS (lipopolysaccharide)

Question 29

What is special about Type 2 TI antigens? What is our example?

Answer 29

• Can’t provide signal 2, but can recruit things to provide signal 2
• Bacterial capsule polysaccharides

Question 30

How old before children generate effective TI responses?

Answer 30

2 years (recall requires MZ B-2’s)

Question 31

Which B cells mount TI responses? Why?

Answer 31

• B-1 and MZ B-2’s

- Antibodies for microbial pdt’s, anatomic location, rapid response

Question 32

What 3 ways can Type 1 TI antigens be presented to B cells?

Answer 32

• By the bacteria itself
• By antigen presenting cell
• As dead chunks of bacteria floating around

Question 33

What 2 ways can Type 2 TI antigens be presented to B cells?

Answer 33

• Signal 2 is provided by something else like the PRR for LPS
• Signal 2 is provided by complement (C3b)