Immunology Lecture I

Question 1

What are the important features of the immune system

Answer 1

• Complexity
• Redundancy –we cannot rely on one part of the immune system as pathogens mutate therefore we have lots of different back-ups to deal with infections
• Its basic function is to distinguish between self and non-self – if you can recognise self you can recognise non-self (foreign)

Question 2

what are low grade pathogens

Answer 2

• Bacteria in the gut (10,000 species, 1013 cells)
• Staphylococci on skin
• Klebsiella/Neisseria/pnuemoccic in throat
• When they get in the wrong place without a immune system we die, even with an immune system they can still kill us

Question 3

What does HIV do

Answer 3

• HIV kills immune system (T cells) patients die of opportunistic infections such as pneumocystis carinii, cryptosporidium, atypical mycobacteria,
• Wasting disease in chronic diarrhoea – in HIV

Question 4

what are the two types of immunity

Answer 4

adaptive immunity

innate immunity

Question 5

what happens if you are born without an immune system

Answer 5

• The immune system is very complex, with lots of different problems but most extreme is having a lack of lymphocytes
• A baby with SCID may have recurrent bacterial, viral, or fungal infections that are more serious and less responsive to treatment than would normally be expected
• These include ear infections, sinus infections, oral thrush, skin infections, meningitis and pneumonia
• Infants with SCID may also have chronic diarrhoea
• They have a bone marrow transplant to treat the immune system

Question 6

How do you get an immune system from bone marrow

Answer 6

• In the bone marrow there is a pluripotent stem cell, this undergoes slow division
• This cell can give rise to allow the cells in the immune system
• The pluripotent stem cell can become a lymphoid stem cell and give rise to B and T cells (this is adaptive immunity)
• It can then become a monoblast and is converted to eosinophil basophil, neutrophil, and monocytes (this is innate immunity)
• It can become a megakaryocyte which is then converted to thrombocytes
• And it can become an erythrocyte

Question 7

How does the adaptive immunity work

Answer 7

• Lymphoid stem cell stems from pluripotent stem cells
• Go to B cell and T cells
• B cells make antibodies by haematopoiesis – if people don’t have antibodies as you can give them back to them by using other peoples antibodies
• T cells can be divided into CD4 helper and CD8 cytotoxic
• T cells are more important than B cells as when they stop working they die

Question 8

describe the structure of the antibody

Answer 8

• Heavy chain
• Light chain
• Variable region
• Constant region
• Disulphide bond

Question 9

Describe where T and B cells originate from

Answer 9

• T cells mature in the thymus

- B cells are made in the bone marrow

Question 10

What are primary lymphoid tissues

Answer 10

means the activity of the bone marrow and thymus occurs in the absence of antigens, so during development in the uterus the thymus and bone marrow were making antibodies, at this stage you are not exposed to antigens

Question 11

what does the size of secondary lymphoid tissues depend on

Answer 11

• size depends on antigenic exposure - they swell up when you get an infection

Question 12

Name some secondary lymphoid tissues

Answer 12

• These include tonsils, lymph nodes, lymphatic vessels, liver, spleen, peyers patch on small intestine, appendix area

Question 13

what are the key concepts in immunology

Answer 13

1. The immune system recognises pathogens by responding to non self – (self v non self)
2. an antigen is anything which elicits an adaptive immune response there are two types, self antigen and foreign antigen
   - self antigen is when the immune system starts to respond to itself this is a autoimmune disease
   - foreign antigen is when the antigen comes from outside you
3. the adaptive immune system shows exquisite specificity – it recognises single things at low levels
4. the immune system has memory – remembers the infection before, have enough cells to respond quickly

Question 14

How does the adaptive immune system recognise something that is foreign

Answer 14

• A T or B cell has on its surface a antigen receptor
• antigen specific T cell receptor TcR
• antigen specific B cell receptor BcR
• when these cell recognise an antigen they undergo massive cell division and then become effectors this is adaptive immunity

Question 15

how does the innate system recognise that something is foreign

Answer 15

• limited number of receptors, 2 different times
• phagocytes – pattern recognition receptors (PRR)
• Fc receptors they do their business immediate (innate immunity)

Question 16

what are the receptors in the innate immune system

Answer 16

• phagocytes – pattern recognition receptors (PRR)

- Fc receptors they do their business immediate (innate immunity)

Question 17

describe the process of innate immunity

Answer 17

• Bacteria binds to TLR
• This signals to the macrophage which turns on genes and this causes the local production of cytokines such as TNF-alpha and IL-1 beta
• This causes the vessel to become sticky as cytokines increase adhesion molecules
• This causes neutrophils to be release
• neutrophil in blood spends all the time in the blood, they are not in the lymph nodes
• has to move into the tissue fluid to get rid of the pathogen

Question 18

How does the macrophage know that the bacteria is there

Answer 18

• pathogen associated molecular patterns

- in the cell wall there are cells that are not expressed in the human Body this enables them to be recognised

Question 19

what are toll like receptors

Answer 19

• These are receptor molecules on the surface of mammalian cell which recognise the components of bacteria and virus to alert the immune system-10 of them (tells the immune system there is an infection

Question 20

name the examples fo toll like receptors

Answer 20

• T LR2 – lipoproteins
• TLR4- LPS (Gram negative bacteria) F protein
• TLR5 - flagellin
• TLR9 – CpG DNA
• TLR7 – recognises double stranded viral RNA
• Cells are converted in these receptors such as epithelial cells and phagocytes

Question 21

what happens when toll receptors become activated

Answer 21

• They become activated and starts to make pro-inflammatory cytokines
• Septic shock is when you make so many cytokines due to an over expression of the toll like receptors

Question 22

what is inflammation

Answer 22

• Inflammation is when white cells leave the blood and move into the tissues and in the process of getting rid of the bugs, kill normal tissues as well

Question 23

what type of WBC are neutrophils

Answer 23

phagocytes

granulocytes - they are filled with granules

Question 24

why do neutrophils cause inflammation and kill normal tissues

Answer 24

they produce these molecules which are toxic therefore this destroys normal tissues as well

• Free radicals
• Neutrophil elastase
• Neutrophil collagenase
• Myeloperoxidase – causes pus to be yellow
• Gelatinases
• Anti-bacterial peptides
• Cytokines

Question 25

what is slower the innate or adaptive immunity

Answer 25

adaptive immunity

Question 26

what happens if the bacteria gets into the CSF

Answer 26

starts to multiply really fast and you die of sepsis

Question 27

Describe adaptive immunity

Answer 27

• At birth have T and B cells ready to fight for foreign antigens so we are ready for any infection
• There is as 1013 cells in the body and we cannot devote them all to the immune system
• 1 in 100 cells in the body is lymphocyte
• For each specific antigen only have about 500 cells that can recognise it
• We only have a few cells for each antigen
• So we need to make sure that the cells need to see a pathogen quickly

Question 28

What happens when a B ell becomes activated

Answer 28

• Divides really fast – makes lymph nodes bigger
• Clonal expansion
• Make antibodies from the plasma cells
• ER makes 2 micrograms of antibodies a day
• Some cells become memory cells
• This expansion depends on T cells

Question 29

What happens when a T cell is activated

Answer 29

• Controlled by IL-2 – this feeds back
• Clonal expansion
• Makes memory and mediate immunity cells

Question 30

describe vaccination

Answer 30

After vaccination we make memory cells and these are immunological different and are called primed cells
They divide really fast and get many more lymphocytes and they have long term immunity meaning that they can divide quickly and produce antibodies and this means that you cannot get the disease

Question 31

describe modern immunity

Answer 31

• Cells have to know where they are and what’s around them and the molecules that affect the cells
• Surrounded by ECM
• All cells are covered in receptors,
• Receptors transmit signals from the cell surface to the nucleus to change gene expression and function
• Receptors can be blocked this is what we use to treat diseases

Question 32

How do we treat the immune diseases

Answer 32

Treat immune diseases with drugs that inhibit the immune system or antibodies that target the immune molecules causing the damage (monoclonal antibodies