L6 - generation of antibodies

Question 1

cartwheel nucleus

Answer 1

DNA open in specific regions (this is what happens when it differentiates into plasma cell, ensure the nucleus is open to allow generation of genes that can produce antibody)

Question 1

what cell makes the antibody

Answer 1

plasma cells

Question 2

what cells in the bone marrow allow rearrangement of Ig and how

Answer 2

stromal cells
via IL-6 and 7

Question 3

why is IgM first expressed on b cells

Answer 3

the default class of BCR in early cell development

Question 4

other than IgM, what is the other first Ig on the surface of B cells

Answer 4

IgD

Question 5

what is CD19

Answer 5

surface protein on b cells, can be used for identification

Question 6

what is the 2 signals needed for B cell activation

Answer 6

• recognition of specific antigen to the membrane Ig molecule
• interaction with CD4 T cell (T cell dependent stimulation

Question 7

2 ways the T follicular helper cells allows interaction with b cell

Answer 7

First is interaction via CD40
And the other is production of cytokines that allow survival and proliferation of B cells (IL-4)

Question 8

where are the macrophages in the lymph node

Answer 8

marginal zone
(where free flowing antigens are collected

Question 9

what is cross linking

Answer 9

multiple Ig on the surface of the cell need to be stimulated to activate the b cell

Question 10

what happens after B cell becomes activated

Answer 10

starts to move towards the border of the cortex and paracortex
The paracortex is where the t cells are (these will also be activated at this point via the antigens on dendritic cells)

Question 11

what happens in the medullary cord

Answer 11

The activated B and T cells get to the medullary cords and form the primary foci

Question 12

what happens to the antigen the b cell encounters

Answer 12

internalises it
presents its peptides on MHC class 2 molecules

Question 13

how can the t cell deliver the second signal to the b cell

Answer 13

it will recognise the peptide antigen presented on the B cell
so this is the T cell dependent stimulation

Question 14

how does the t cell direct the release of the cytokines after interaction with the b cel

Answer 14

reorients its cytoskeleton and secretory apparatus towards the b cell
so the release of the cytokine in confined to the space between the b and t cell

Question 15

what type of cell do primary follicles in the lymph node contain

Answer 15

follicular dendritic cell (FDC)

Question 16

what are FDCs derived from

Answer 16

stromal cells

Question 17

where do FDCs hold the antigen-antibody complexes

Answer 17

iccosomes

Question 18

why do the FDCs hold antigens on their surface for extended amount of time

Answer 18

provides antigen to the b cell during the forrmation of the germinal centres

Question 19

what happens in germinal centre

Answer 19

where affinity maturation and class switching occurs

Question 20

centroblasts

Answer 20

located in the dark zone of germinal centre
cell has down regulation of Ig membrane receptors
start proliferating extensively

Question 21

affinity maturation

Answer 21

where high affinity antibody is made

Question 22

what reegion of the centroblasts undergo hypermutation

Answer 22

H and L chains of their Ig molecule
so change in structue of the hypervariable region

Question 23

what happens when centroblasts stop dividing and re-express their surface Ig

Answer 23

turn into centrocytes

Question 24

what do centrocytes do

Answer 24

move towards the FDCs
if they bind the antigen on the FDC with high affinity = srvival signal

Question 25

what happens to the surviving centrocytes

Answer 25

meet up with the activated T helper cells and differentiate into plasma cells that secrete the high affinity atnibody
OR
turn into memory B cells

Question 26

where are the centrocytes located

Answer 26

in the basal light zone

Question 27

where are the plasma cells and memory cells located

Answer 27

apical light zone

Question 28

what is another thing that happens during the centroblast centrocyte drama

Answer 28

class switching

Question 29

what is class switching

Answer 29

where the B cell is able to change its heavy chain constant region from µ (IgM) to γ (IgG) or α (IgA) or ε (IgE) whilst keeping the same heavy chain variable and light chain (the antigen binding parts)

Question 30

what is class switching controlled by

Answer 30

CD4 T cells and cytokines
(without the CD40 CD40L interaction the t cell has with the b cell, can only make the IgM)

Question 31

what does IL-4 induce (antibody class)

Answer 31

IgE

Question 32

what else do cytokines do in calss switching

Answer 32

influence the type and how much AB is made

Question 33

what signal from the T cell has been implicated in the differentiation of plasma and memory cellss

Answer 33

CD154/CD40 signal
(plasma cell is the default but then with this signal it turns into memory cell but still dk fully)