Lymphoid tissues

Question 1

Lymphatic system components?

Answer 1

Lymphatic vessels and secondary lymphoid tissue.

Question 2

Examples of lymphocytes.

Answer 2

T cells, B cells and natural killer cells.

Question 3

What are primary lymphoid tissues?

Answer 3

This is where production of lymphocytes takes place (lymphopoieses).

Question 4

Primary lymphoid organs.

Answer 4

Thymus, Bone marrow and foetal liver.

Question 5

What are the two hallmarks of the adaptive immune system?

Answer 5

Specificity and memory.

Question 6

What does ‘repertoire’ mean in immunology?

Answer 6

The range of genetically distinct BCRs or TCRs present in a given host.

Question 7

Where is the b cell repertoire generated?

Answer 7

Bone marrow.

Question 8

Where do B cell mature?

Answer 8

Start of maturation occurs in bone marrow where B cell progenitor is created. Final maturation occurs in periphery in spleen or lymph nodes.

Question 9

Where does t cell repertoire occur?

Answer 9

Thymus.

Question 10

What is positive selection?

Answer 10

Does the T cell recognise non self antigens.

Question 11

What is negative selection?

Answer 11

Does the T cell recognise self antigens. If so then cell apoptosis takes place.

Question 12

What is thymic involution?

Answer 12

Shrinking of thymus with age. Thymic output decreases with age.

Question 13

What are secondary lymphoid organs?

Answer 13

Secondary lymphoid organs are where lymphocytes interact with antigens and other lymphocytes.

Question 14

Secondary lymphoid organs.

Answer 14

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

Question 15

Properties of lymph nodes.

Answer 15

Distinct T and B cell regions. Afferent(in) and efferent(out) lymp vessels. Arterial and venous connections. Contain germinal centres.

Question 16

What is a germinal centre?

Answer 16

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

Question 17

What is the secondary lymphoid tissue within the gut?

Answer 17

Peyer’s patches.

Question 18

What are peyer’s patches?

Answer 18

A follicle highly enriched with B cells and contain a high frequency of germinal centres.

Question 19

Why are peyer’s patches and the tonsils always active?

Answer 19

Exposed to lots of antigens.

Question 20

Where in the gut are peyer’s patches found?

Answer 20

Below epithelium in Ileum.

Question 21

How do naïve T cells enter lymph nodes?

Answer 21

Selectin binding to endothelial cells. Switch to integrin binding. Transendothelial migration through high endothelial venule.

Question 22

Through which specialised vessels do naive lymphocytes leave the blood to enter lymph node?

Answer 22

High endothelial venule.

Question 23

What is an antigen?

Answer 23

Any molecule capable of generating an adaptive immune response.

Question 24

How do antigens get from the site entry to our lymph nodes?

Answer 24

Diffusion and antigen presenting cells.

Question 25

Main type of antigen presenting cell?

Answer 25

Dendritic cell.

Question 26

What antigen presenting cell is found in the epidermis?

Answer 26

Langerhans cells.

Question 27

What is antigen presentation?

Answer 27

The display of peptides in the major histocompatibility complex I or II proteins such that the T cell receptor can attempt to bind them.

Question 28

What does ‘CD’ mean? e.g CD19

Answer 28

Cluster of differentiation. Systematic naming of proteins used in the phenotyping of hematopoietic cells.

Question 29

What CD protein do all T cells have?

Answer 29

CD3.

Question 30

Where would you find dendritic cells?

Answer 30

Tissues, lymphatics, and secondary lymphoid organs.

Question 31

What molecular process is the basis of high affinity maturation? How does this process occur?

Answer 31

Somatic hypermutation. An enzyme called activation-induced cytidine deaminase (AID) makes random mutations in the antibody variable region genes. If the mutations result in an antibody that more strongly binds to their targets then these B cells will survive and may differentiate into antibody-producing plasma cells with the new specificity.