4

Question 1

What B cells are there

Answer 1

B1
B2- gc B cells
Mz B cells

Question 2

What are B1 cells involved in

Where are they found

Answer 2

Natural antibodies production ( early protection), express toll like receptors for common bacterial ligand and recognise self
Can also generate memory B cells during T cell indpendant immune response
Coelomic cavities lamina propria - milky spots FALC

Question 3

At what point do mz B cells come from b2 cells

Answer 3

At the immature be cell stage

Question 4

What are natural antibodies

Answer 4

Germ-line coded not affinity matured
Mostly igM some igG and igA
Can bind to proteins carbohydrates lipid and nucleic acids

Question 5

Comparing b1 cells and classical B cells what are they both clustered around

Answer 5

B1 reticular networks of macrophages

Reticular networks of FCDS

Question 6

What are MZ B cells for

Answer 6

Antigen independent hypermutarion to generate a predict raided set of B cells receptors
Rapid igM responses- especially to pathogens that don’t trigger classical t dependant responses

Question 7

What are the two ig types that B cells can become

Answer 7

IgM - Unswitched, gc independent memory B cells

IgGa plasma cells

Question 8

Which igs are in secretions

Answer 8

IgA igM

Question 9

Which igs are in serum

Answer 9

IgG igA igM igD

Question 10

Why is igE not normally found in circulation

Answer 10

Binds very tightly to fc region on basophils and mast cells or coats helminths

Question 11

Which igs are produced first and by memory cells

Answer 11

IgM and igD

Question 12

Which igs have to have been class switched to

Answer 12

IgG igA igE

Question 13

How are long lived plasma cells displaced from their niches

Answer 13

New ones being formed

Question 14

Where do most activate B cells reside

Answer 14

Adult gut mucosa

Question 15

What are the two major general properties shared by newly generates T cells

Answer 15

I leave the thymus in a naive state

Can circulate through secondary lymphoid tissues - thymic development imprints the tissue tropism of T cell subsets

Question 16

What is the difference between adaptive T cell and innate like T cells

Answer 16

Adaptive require T cell clonal expansion and are slow

Innate like can sense and respond to infections or stress quickly without need for expansion or differentiation

Question 17

Which are the conventional T cells

Answer 17

Cd4
Cd8 
Nkt
Gem t
MAIT

Question 18

What are he two hypothesis for fate decision of CLPs

Answer 18

Default- all conventional some differentiate to non conventional
Exclusion- all unconventional, some switch off unconventional genes and differentiate

Question 19

Thymic epithelial development is under the control of what

Answer 19

FoxN1 transcription factor

Question 20

What makes the thymic connective tissue o

Answer 20

Mesoderm and neural crest

Question 21

What is the general structure of the thymus

Answer 21

2-3 lobes

Capsule with septa/ trabeculae dived into lobules making a Cortes and continuous central core- medulla

Question 22

What happened during involution of the thymus

Answer 22

Epithelial component atrophied - small scattered lymphocytes in abundance adipose

Question 23

What it the cell population in the cortex of the thymus

What is special about this area

Answer 23

Thymocytes and comical epithelial cells

Has blood- thymus barrier and is isolated from self- antigens

Question 24

What creates the the blood thymus barrier

Answer 24

Subcapsular epithelial cells lining trabeculae
Cortical blood vessels lined by cortical epithelial cells
Corticomedullary junction rich in antigen- capturing dendritic cells
Closed capillary type

Question 25

What cells populate the medulla of the thymus

Answer 25

Medullary epithelial cells
Dendritic cells
Macrophages
Some thymocytes

Question 26

Which cells are responsible for postitive and negative selection in the thymus

Answer 26

Postitive- cortical epithelial cells

Negative- medullary epithelial cells dendritic and macrophages

Question 27

What is a hassalls corpuscle

Answer 27

Central mass of one or more granular cells
Appear in medulla after lymphopoiesis has been established
Secrete thymic Stromal services lymphopoietin
Induced conversion of self-reactive cd4 thymocytes to natural regulatory T cells

Question 28

What are the stages of alpha beta T cell development

Answer 28

Double negative in the Cortex cd4-/cd8-
Double postitive- cortex
Single positive in the medulla cd4+ or cd8+

Question 29

What are the two main check points in the inter thymic development of T cells

Answer 29

Positive selection- rejecting the useles that don’t bind to MHC
Negative selection- prevent the harmful
Only those T cells survive which do not bind to self antigens

Question 30

What characterises medullary epithelial cells

Answer 30

Expression of gene expression of tissue specific genes, ubiquitously expressed proteins and abundant blood borne self-antigens

Question 31

What are the stages of ab T cell development

Answer 31

Dn progenitors entree thymus at corticolmedullar you junction
DN cells proliferate and acquire lineage specificity in the cortex = DN 2
DN 3 commit to T cell lineage in sub capsular zone ( ab and yd separate)
DN 4 proliferate and transition to DP cells, migrate back through cortex
DP - positive selection by interaction with cortex epithelial cells
MAIT and NKT cells separate from cd4/8 migration to the medulla
SP- negative selection by mTECs and DCs
Naive T cells exit the thymus to migrate to secondary lymphoid organs

Question 32

From T cells what can be formed

Answer 32

Innate lymphoid cells ILC
Cd8aa ydt
abT- cd8+ cd4+ (non MHC ILC )

Question 33

What is it that generates the cd4 T cell sunsets

Answer 33

Cytokines environment