B cells: activation

Question 1

Where do all these interactions happen

Answer 1

B cell activation, differentiation and proliferation = in ln
But each in diff parts ln
B cells migrate to diff regions of ln during diff stages
Signals direct B cells to appropriate locations at each diff stage (chemokines)

Question 2

Subscapular sinus

Answer 2

Outer portion
Where scs macrophages located and encounter ag

Question 3

T cell zone

Answer 3

Where T cells get activated by interacting with dcs

Question 4

B cell zone

Answer 4

Includes B cell follicle = where germinal centres can form
Where B cells encounter ag and and undergo later stages of proliferation and differentiation - including in B cell follicles and germinal centres

Question 5

T-b border

Answer 5

Border between b and T cell zones
= where B cells first get signal 2

Question 6

Describe follicle

Answer 6

Development of B cells = where they get activated

Question 7

Describe germinal centre

Answer 7

Site of intense B cell differentiation and proliferation - forms inside follicle

Question 8

Where does B cell encounter ag

Answer 8

B cell can encounter ag On scs Macrophages, free floating or on follicular dcs (in B cell zone)

Question 9

Describe what happens after B cell encounters ag - increases of wat

Answer 9

Bcr:ag internalized and processed
Increased expression mhc2
Increased expression of chemokine recpetor —> targets B cell to t-b border

Question 10

What targets B cell to t-b border

Answer 10

Increased expression of chemokine recpetor —> (if tfh finds match) targets B cell to t-b border = where B cell receives signal 2 and becomes activated

Question 11

Name the choices activated B cells have

Answer 11

Forms primary focus in subscapular region
Or
Migrate to follicle to form germinal centre

Question 12

Describe option 1 = form primary focus

Answer 12

Form primary focus
Near subscapular region = differentiate into plasmablasts

Question 13

Describe option 2 = form germinal centre

Answer 13

Go to follicle to form germinal centre - gc reaction
Differentiate into plasma cells - secrete abs with higher affinity (for ags) than plasma blasts

Question 14

Are plasmablasts the same as plasma cells

Answer 14

NAAAAAAAHHHHHHHHH

Question 15

Describe naive B cells

Answer 15

BEAR cell surface igm - bcr membrane bound
Do not secret ab

Question 16

Describe plasma blasts

Answer 16

Differentiated B cells
Have begun to secrete abs - secrete igm abs
Can still proliferate
Still bear cell surface bcr

Question 17

Describe plasma cells

Answer 17

Differentiated B cells
Can no longer divide
Little/no cell surface immunoglobulin
Rapidly secrete large numbers of abs (higher affinity abs and diff classes of abs)

Question 18

Plasmablasts from

Answer 18

Primary focus

Question 19

Plasma cells from

Answer 19

Germinal centre reaction

Question 20

At primary focuse what are the 2 main outcomes

Answer 20

Plasma blast (most do this) = early ab production - Mainly igm (bcrs on surface then secreted)
Or
Igm+ memory B cell - production of igm

Question 21

Where is primary focuse

Answer 21

Activated B cell that has received signal 1 and 2 = migrates to form primary focuse near subscapular zone or in interfollicular regions or medullary cords

Question 22

What happens in primary focus

Answer 22

Activated B cells undergo proliferation and differentiation into plasmablasts

Question 23

When are primary foci apparent

Answer 23

About 5 days after primary infection

Question 24

What are plasma blasts - gen

Answer 24

B cells that secrete abs
Responsible for early ab production - mainly igm
Igm produced

Question 25

What are plasma blasts - die?

Answer 25

Most plasma blasts in primary focus die within 5-10 days

Question 26

What are plasma blasts - what can some do

Answer 26

Some can migrate to bone marrow and become plasma cells - where they continue ab production - for longer (rare)

Question 27

Describe outcomes at germinal centre

Answer 27

Plasma cell = secrete large amounts abs Or Memory B cell = important for memory response, maintain capacity to produce high affinity abs

Question 28

Describe plasma cells - what is diff

Answer 28

Plasma cells secrete abs with higher affinity And can secrete all diff classes of abs

Question 29

What happens at germinal centre

Answer 29

B cells recieve signals 1 and 2 again B cells undergo differentiation and processes to produce abs that are more effective and have affinity

Question 30

Describe differentiation processes that happens in germinal centre

Answer 30

Somatic hypermutation Affinity maturation Class switching

Question 31

When does size germinal centre peaks

Answer 31

Size of germinal centre peaks 7-12 days after infection - takes longer than primary focus

Question 32

Describe where plasma blasts go

Answer 32

Mostly stay in lymph node and secrete abs

Question 33

Describe what plasma blasts do - summarize

Answer 33

Early ab production Abs have lower affinity, mostly igm Die fast

Question 34

Describe where plasma cells go

Answer 34

Can either say in ln medulla Or travel to bone marrow and reside there and continue to secrete abs

Question 35

Describe what plasma cells do - summarize

Answer 35

Produced a bit later Higher affinity After class switching (not igm)

Question 36

What can both plasma cells and plasma blasts do

Answer 36

Both cell types can migrate to site of infection too = produce abs

Question 37

Germinal centre aka

Answer 37

Secondary lymphoid follicle