1. Pre Course tutorials

Question 1

What are the bodies first line of defence against pathogens?

Answer 1

Skin, 
stomach acid
muco-ciliary escalator 
Lysozyme
Mucocilary 
Intact mucosal membranes 
Acidic pH of stomach 
Rapid pH change in duodenum and alkaline pH in jejunum and ileum 
Normal flora and bowel and vagina and on the skin surface 
Flushing of urinary tracts

Question 2

What are the major components of the immune system?

Answer 2

Lymph nodes
Lymphatic vessels
Lymphatic ducts
Spleen, bone and the thymus

Question 3

What are the two major types of cells involved in cell genesis

Answer 3

Common myeloid cells and common lymphoid cells

Question 4

What do the common myeloid progenitor cells go on to produce?

Answer 4

Magakaryocyte(large myeloid cell found in bone marrow)——-> platelets
Erythrocyte
Mast cell
Myeloblast———> erythrocytes

Question 5

What do the common lymphoid progenitors differentiate into?

Answer 5

Natural killer cell (large granular lymphocyte)- activated by abnormal MCH1 signals. Granules contain special proteins such as perform and protease

Small lymphocyte———-> T lymphocyte and B lymphocyte —-> plasma cell

Question 6

What are the different cells that myeloblasts differentiate into and what do they do?

Answer 6

Basophils-
Neutrophils- contains digestive enzymes, first responders
Eosinophils-
Monocyte-

(From the monocyte)

Macrophage-
Dendritic cell-

Question 7

Describe the innate immune system?

What cells are involved?

Answer 7

The rapid response to infection, they display no immunological memory. Comprised of:

Phagocytes
Dendritic cells
Complement cells- enhances antibody and phagocytose response
Natural killer cells

Question 8

Describe the adaptive immune system

Answer 8

Comprised of the response from B and T lymphocytes:

B lymphocytes-> differentiate into plasma cells and form antibodies to the pathogen

T lymphocytes are presented the antigen by antigen presenting cells (APC’s) and create effector T cells which attack the pathogen

Question 9

What is an antigen?

Answer 9

A marker on every cell that differentiates itself from other cells.

Question 10

What is the major histocompatability complex I or (MHC I)?

Answer 10

An antigen present in every single nucleated cell. They display their own unique fingerprint to signal to the bodys antibodies that they’re okay. In cancer or damaged cells the MHC1 complex presents an abnormal endogenous (intracellular) antigen which antibodies recognise as an abnormal fingerprint and destroys the cell.

Also called the human leukocyte antigen or HLA

Question 11

What is the function on the major histocompatability complex II or class II MHC?

Provide examples of cells that contain class II MHC

Answer 11

Found on “professional antibody presenting cells” they are responsible for presenting exogenous or extracellular antigens from pathogenic invaders. Examples of pro antibody presenting cells included dendritic cells, macrophages and B lymphocytes. The antigen presenting cells take the extracellular antigens and present them to the T cells.

Question 12

What are CD4 T lymphocytes?

Answer 12

Antigen presenting cells present their exogenous antigen to CD4+ T helper lymphocytes. They produce CD4+ cytokines. These signal to B lymphocytes to release specific antibodies against the foreign invader. It also improves macrophage phagocytosis and recruits primer CD8+ cells to target the foreign invader directly

Question 13

What are CD8+ cytotoxic T lymphocytes?

Answer 13

Any nucleated cell can present their antigens via MHC1 molecules to CD8 cytotoxic T lymphocytes.

Question 14

What is immunological tolerance?

Answer 14

The immune system learns to be tolerant or unresponsive to a particular antigens. Typically this is the body tolerating its own self antigens.

Question 15

How is central tolerance developed?

Answer 15

Delvoped in primary lymphoid organs, cells learn to differentiate between healthy and unhealthy cells. Cells that do not pass the test are edited or destroyed

B cells- develop central tolerance in the bone marrow
T cells- develop central tolerance in the Thymus

Question 16

How is peripheral tolerance developed

Answer 16

Created when secondary lymphoid organs containing mature immune cells are released into circulation. If any of these cells become inappropriate then they are made useless and destroyed

Question 17

What are the different classes of lymphoid organs?

Answer 17

Primary- Thymus, bone marrow

Secondary- Tonsils, lymph nodes, Peyers, patches, Spleen,mucosa-associated lymphoid tissue (MALT)

Question 18

What cells are not capable of phagocytocis

Answer 18

Eosinophils

Question 19

What cells recognise a virally infected host cell

Answer 19

Natural killer cell

Question 20

What 3 cells are vital for targeting parasites or organisms too large for phagocytosis?

Answer 20

Mast cells
Basophils
Eosinophils

Question 21

What are the two responses of the adaptive immune system?

Answer 21

Cell mediated responses- orchestrated by T lymphocytes

Humoral repsonses - using antibodies formed by T-lymphocytes

Question 22

What are the cells of the adaptive immune system?

Answer 22

Common lymphoid progenitor
Small lymphocyte 
T and B lymphocyte 
T Cells—> CD4 and CD8
B lymphocyte- plasma cell and memory B cell

Question 23

What further cells of the adaptive immune system are developed in secondary lymph tissue?

Answer 23

CD4+ T helper cells——> TH1, TH2, TH17

CD8+ cytotoxic T cell

Question 24

What is a T cell receptor?

Answer 24

A structure unique to T lymphocytes, the part that binds to the antigens are called complementary determining regions (CDR’s)

Question 25

What is V(D)J recombination

Answer 25

A process of genetics change that creates a diverse selection of antigen binding sites within the TCR. Therefore when the T cells are released from the thymus they have more chance of recognising an antigen

Question 26

What does CD stand for?

Answer 26

Cluster of differentiation. CD4 and CD8 are cell markers on T lymphocytes, they act as co-receptors with the TCR. This means they help the TCR interact with the MHC more effectively

Question 27

What does the process of development look like for the T lymphocytes?

Answer 27

``` Begin as completely undifferentiated CD- cells. Change into CD positive cells First they must prove they can interact with the MHC Then they must prove they can react appropriately to a self antigen Finally depending on if they recognise a MHC class 1 or class 2 antigen they are differentiated into singe positive T cells. ```

Question 28

How can T cells proliferate?

Answer 28

They proliferate and differentiate into different T cells when they encounter cytokines presented on antigen presenting cells in secondary lymphoid organs such as lymph nodes.

Question 29

What are the three types of T cells?

Answer 29

Antigen presenting T cells, Regulatory T cells Cytotoxic T cells

Question 30

What is the job of cytotoxic T cells?

Answer 30

Recognise any virally infected host cells, malignant cells or any cells that shows damage vie their MCH1 expression

Question 31

What are the different way cytotoxic cells (CD8) can act?

Answer 31

They can release interferon and tumour necrosis factor alpha which have direct antiviral and anti tumour effects They can release cytotoxic granules which contain perforin and granzyme proteins in the direction of target cells. Perform produces a pore in the bacteria allowing the granzyme enzymes to enter Induces apoptosis through Fas and FasL interactions in the pathogenic cell

Question 32

What are the job of T helper cells (antigen presenting/CD4+)

Answer 32

They help activate other immune cells by releasing T cell cytokines to wither stimulate or regulate the immune response. Responsible for B lymphocyte antibody class switching Responsible for the activation and growth of cytotoxic T lymphocytes and they maximise the activity of phagocytes.

Question 33

What are the three classes of helper T cells?

Answer 33

TH1 TH2 TH17

Question 34

What is the job of TH1?

Answer 34

Clearance of intracellular pathogens through interferon gamma which maximises the response of cytotoxic T cells and macrophages They also inhibit Th2 responses.

Question 35

What is the job of TH2 cells?

Answer 35

Important for the response to extracellular pathogens. They release interleukins 4,5 and 13. This results in esinophil, basophils and mast cell activation. Promotes class switching of antibodies to IgE. Th2 cells inhibit the TH1 response

Question 36

How does an imbalance of Th1 and Th2 cells lead to disease?

Answer 36

Overactivity of Th1 cells against autoantigens leads to type 4 hypersensitivity reactions. Such as MS Overactivity of Th2 cells leads to type 1 hypersensitivity reactions such as asthma

Question 37

What is the role of TH17 cells?

Answer 37

Release interleukin 17 which stimulates the recruitment of neutrophils and macrophages. They also maintain mucosal barriers. If TH17 cells are overactive this results in a pro-inflammatory state as seen in rheumatoid athritis

Question 38

What do regulatory T cells do?

Answer 38

Can be induced in periphery or in thymus in cells that recognise self antigens. They’re role is to suppress the activation and proliferation of CD4 and CD8 lymphocytes. In addition they control the response to self antigens and self tolerance. They secrete Il10 and transforming growth factor beta which are anti inflammatory and suppress the immune response.

Question 39

What is humoral immunity?

Answer 39

Immunity in fluids of the body. B lymphocytes are responsible for this through the actions of antibodies directed against specific antigens. It is part of the adaptive immune system