Lymphoid tissues

Question 1

Where do T cells undergo final development ?

Answer 1

Thymus

Question 2

Where do B cells undergo maturation?

Answer 2

Bone marrow

Question 3

What are the two types of immunity?

Answer 3

Specific and memory

Question 4

What are the specialised receptors for T cells?

Answer 4

TCRs (T-cell receptor)

Question 5

What are the specialised receptors for B cells?

Answer 5

BCRs (B-Cell receptors)

Question 6

Where does the B-cell progenitor stage occur?

Answer 6

Bone marrow

Question 7

How are B cell receptor variable regions form?

Answer 7

Multiple copies of V,D and J genes can be rearranged in different combinations, contributing to diversity
Distinct V and J genes

Question 8

What genes are responsible for the heavy chains?

Answer 8

D genes

Question 9

What happens to the BCR upon antigen recognition?

Answer 9

Somatic hypermutation occurs; resulting in antibody with greater affinity to the target, B cells will subsequently differentiation into plasma cells (antibody-producing).

Question 10

Which enzyme is used to promote mutations in antibody variable region gene?

Answer 10

Activation induced cytidine deaminase (AID)

Question 11

What does CD mean?

Answer 11

Cluster of differentiation, CD proteins specific to particular lymphocyte

Question 12

What are primary lymphoid tissues?

Answer 12

sites where lymphocytes are produced, supporting lymphoid-progenitor cute, cells that mature into B and T cells (helper and NK)

THYMUS, Bone marrow and foetal liver

Question 13

What is the primary site of haemopoesis?

Answer 13

Bone marrow

Question 14

Which cells do HSC differentiate into?

Answer 14

Lymphoid and myeloid progenitor cells

Question 15

Where does further maturation proceed?

Answer 15

In the periphery

Question 16

Where is the B cell repertoire generated?

Answer 16

Bone marrow

Question 17

Which factor stimulates increased white cell production during infection?

Answer 17

Granulocute-colony stimulating factor

Question 18

What is the definition of a repertoire?

Answer 18

Range of genetically distinct BCRs, or TCRs, present in a given host (larger the repertoire, the greater the number of recognisable threats)

Question 19

Where do the lymphoid progenitors migrate to for antigen-independent maturation?

Answer 19

Thymus gland

Question 20

Which specific T cell marks develop within the thymus?

Answer 20

TCR, CD3, CD4/8 and CD2

Question 21

What is positive selection ?

Answer 21

Identifies whether T cells have successfully rearranged their TCR⍺ locus, and are capable of recognising peptide-MHC complexes with appropriate affinity. Positive T bind to cortical epithelial cells expressing Class I, or Class II MHC (+ self peptides) with high affinity to provide a survival signal.

Question 22

Which complexes are recognised by TCRs during maturation the Thymus gland?

Answer 22

Peptide-MHC complexes (Class I and II MHC + self peptides)

Question 23

Which cells do positive T cells bind to?

Answer 23

Cortical epithelial cells

Question 24

Which signal is produced upon high affinity binding during positive selection?

Answer 24

Survival signal

Question 25

Where does negative selection occur?

Answer 25

Medulla thymus

Question 26

What is negative selection?

Answer 26

Destroys T cells that bind too strongly to self-antigens expressed on MHC. Cells undergo apoptosis.

Question 27

What is thymus involution?

Answer 27

Shrinkage of the thymus with age. This is associated with a change in structure and a reduced mass

Question 28

What is linked with thymic involution?

Answer 28

T cell regression

Question 29

What effect does T cell regression have?

Answer 29

Thymus declined output

Question 30

What are secondary lymphoid tissues?

Answer 30

Where lymphocytes interact with antigens. Encounter of dendritic cells bearing antigens from peripheral tissues, differentiating into effector and memory cells that eliminate the antigen

Question 31

What are the secondary lymphoid organs?

Answer 31

Spleen, lymph nodes, appendix, mucosal associated lymphoid tissue.

Question 32

How are lymphoid tissues connected?

Answer 32

Interconnected by the lymphatic and circulatory system, exists as discrete organs (lymph nodes adenoids) or distinct regions within a tissue (spleen)

Question 33

How do the secondary lymphoid organs in regards to encountering the antigen?

Answer 33

Enables cells to become in close proximity to antigen.

Question 34

Which cells sample the lymph?

Answer 34

Macrophages

Question 35

What is the purpose of macrophages in secondary lymphoid tissues?

Answer 35

Presents the antigens to T and B cells during T cell activation (Humoral response)

Question 36

Which cells in the lymph nodes produce chemokines?

Answer 36

Fibroreticular cells (fibroblasts)

Question 37

Which chemokines are produced produced by fibroreticular cells?

Answer 37

CCL19, CCL21

Question 38

What effect does CCL19 and ccl2 have on TCRs?

Answer 38

TCRs with integrated CCL7 encouraged to T cell zones of secondary lymphoid tissue- stimulates T cell migration

Question 39

What do lymph nodes do?

Answer 39

Antigen presenting pathogens to be entrapped for T cells to activate and develop immune response against the specific antigens (Lymph nodes filters blood)

Question 40

What zones include in the spleen?

Answer 40

Distinct T and B cells

Question 41

What is the function of the spleen?

Answer 41

Screens the blood for antigens

Question 42

Which ring is formed that encircles the lingual tonsils, oral and nasal cavity?

Answer 42

Waldeyer ring

Question 43

What are specialised lymphoid tissues in the gut?

Answer 43

Peyer's patchers

Question 44

Where are Peyer's patches?

Answer 44

Attached to efferent and afferent limbs | Below the epithelium of the ileum of the small intestine

Question 45

What happens at the general b centre?

Answer 45

Undergoes affinity maturation (antibodies have high affinity for antigens). Patches exhibit germinal activity, generation of B cells and plasma cells producing somatically mutated gut anti-specific IgA antibodies

Question 46

What antibodies are produced by plasma cells derived from gut associated b centres?

Answer 46

Anti-specific IgA

Question 47

What purpose is performed by the anti-specific IgA?

Answer 47

Secreted into the lumen to organise and regulate the intestinal microbiota

Question 48

Which cells are enriched within the follicle?

Answer 48

B cells, high frequency of germinal centres

Question 49

What are germinal centres?

Answer 49

Anatomically restricted, where B cells undergo mutation and selection to generate high affinity antibodies

Question 50

What function does activation -induced cytidine deaminase occur?

Answer 50

``` Promotes class switch recombination (CSR) and affinity maturation through somatic hypermutation Alters variable region to produce high affinity antibodies. ```

Question 51

What type of barrier is the first line of defence in the gut?

Answer 51

Epithelial barriers

Question 52

What is the recirculating time for Naiive T cells?

Answer 52

24 hours

Question 53

How do Naive T cells migrate across?

Answer 53

High endothelial venues (HEV)

Question 54

What cells activate Naive T cells?

Answer 54

Antigen-presenting dendritic cells

Question 55

Which receptors do Naive T cells express?

Answer 55

CCR7 receptors, and adhesion molecules L-selectin & LFA-1

Question 56

Which endothelial protein do L-selectins interact with?

Answer 56

Glycam-1 and CD34

Question 57

What effects does CCL21 binding to CCR7 have?

Answer 57

Conformational change in LFA-1, thus tightly binds to ICAM-1, move through hEV by extravasation, trans-endothelial migration

Question 58

Which complexes do antigen-persenting cells associated antigen peptides with?

Answer 58

MHCI/2