Innate Immunity

Question 1

What is the definition of innate immunity?

Answer 1

The innate immunity system is something we are born with and it is ancient, it is something developed from evolution and is in place before infection and respond in the same way to repeated infections.

Question 2

What is the function of the innate immunity?

Answer 2

The innate immune systems function is to react immediately to microbes and injured cells, it keeps infections in check while activating the adaptive immunity.

Question 3

What are the components of the innate immune system?

Answer 3

The innate immune system is made up of three components: the barrier, cells and soluble molecules.

There are two types of barrier; physical and chemical

There are two types of effector cells; phagocytes and NK cells

Question 4

We have epithelial barriers as part of the innate immune system, how do they work and name some examples.

Answer 4

Epithelial barriers prevent the entry of microbes by producing mucus which have two function: one to coat the microorganism to trap them, two it prevents the microbes to adhere to the epithelium. The epithelial barrier also use cilia to expel pathogens via its movements

Question 5

What are chemical barriers?

Answer 5

They contain antibacterial enzymes such as lysozyme which break down bacteria cell wall by breaking peptidoglycan bonds. Lysozyme can be found in saliva and tears.

They also contain anti microbial peptides such as defensins and epithelial cayjelicidines which kill bacteria by damaging bacterial wall membranes. These are produced by epithelial cells, neutrophils, natural killer cells and cytotoxic T lymphocytes

Question 6

What is microbiological barriers?

Answer 6

This is when our normal non pathologenic bacteria compete with pathogenic bacteria for resources. This explains why after a course of antibiotics we get infection like thrush, this is due to no competition.

Question 7

What is cystic fibrosis?

Answer 7

defective mucus production and inhibition of ciliary movements which result in frequent lung infection

Question 8

What are the effector cells of the innate immune system?

Answer 8

There are two type of effector cells; phagocytes and other cells

The phagocytes include neutrophils, macrophages and dendritic cells. These identify, ingest and destroy pathogens

The there cells include cells worth the lymphoid lineage

Question 9

What does natural killer cells do?

Answer 9

They kill virus infected cells or cells that underwent malignant transformation. They express cytotoxic enzymes.

Natural killer cell contain perforin which creates pores.

Question 10

What’s the difference between natural killer cells and CD8+ T cells?

Answer 10

Natural killer cells can kill malignant tumour cells without prior activation. However CD8+ T cell needs to be activated and differentiated to CTL (cytotoxic T lymphocytes) to kill target cells.

Question 11

Which receptors are responsible for the behaviour of natural killer cells?

Answer 11

Inhibiting and activating receptors.

Natural killer cells interaction with other cells are determined by the integration of signals from inhibitory and activating receptors aka the balance of the signal determine the outcome.

Question 12

Who have MHC I (major histocompatibility complex class I and what does it do?

Answer 12

All healthy autologous uncleared cells have MHC I. Inhibitory receptor from the NK cell recognise MHC I which result in blockade of signal from activating receptors so it doesn’t kill the healthy cells.

Question 13

What does infected cells and malignant cells downregulate?

Answer 13

Malignant and infected cells downregulate MHC I so when these cells are picked up by NK cells they are unable to bind to the inhibitory receptors so signals from the activating receptor are not blocked so NK cells will kill malignant and infected cells.

Question 14

What is ITIM and what does it do?

Answer 14

ITIM is immunoreceptor tyrosine based inhibitory motif

It can be found on the cytoplasmic tails of inhibitory receptors. They engage molecules that block the signalling pathways triggered by activating receptors

Question 15

What are ITAM? What does it do?

Answer 15

ITAM are immunoreceptor tyrosine activation motif

It engage in signalling ever that promote target cell killing and cytokine secretion by NK cell. They are often it located in activating receptors but in cytotoxic portion of adapt or molecules

They normally contains raptor protein which activate the signalling pathway.

Question 16

What does perforin do?

Answer 16

They insert itself through the membrane and cause pores which allow granzymes to enter to initiate apoptosis

Question 17

What does granzymes A,B,C do?

Answer 17

They initiate apoptosis. They do this by activating cascade.
Granzyme B can trigger mitochondrial apoptotic pathway.

Question 18

How does NK cells prevent perforin a and granzymes from killing neighbouring cells?

Answer 18

Granzymes and perforins are deliver at the site of contact on the target cell.

Question 19

What else do NK cells do part from killing?

Answer 19

They activate macrophages to destroy phagocytosis microbes via production of IFN- gamma

Question 20

What is Chediak highashi?

Answer 20

It is a broad immuno deficiency that include NK cell deficiencies.

Question 21

What are phagocytes?

Answer 21

They are specialised cells which identify ingest and destroy pathogens. It is a broader term used to describe neutrophils, macrophages and dendritic cells.

Question 22

What is the role of phagocytes?

Answer 22

Role of phagocytes include protection from pathogens, disposal of damages or dying cells. It also do processing and presentation of antigens. This allows it to activate the adaptive immune system and t acts like a bridge between the innate and adaptive immunity.

Question 23

That are the steps of phagocytosis?

Answer 23

1. Phagocytes mobilisation also know as chemotaxis
2. Recognition and attachment
3. Engulfment l
4. Digestion: pathogen destruction

Question 24

Want are the two type of phagocytes defects?

Answer 24

The defect is quantitative or qualitative. A decrease in number is known a neutropenia.

Question 25

What are some examples of phagocytes defects?

Answer 25

Chronic granulomatous disease
Chediak higashi syndrome
Leukocyte adhesion defects

Question 26

What is chronic granulomatous disease,

Answer 26

This is when a mutation in NaDPH component makes it defective at oxidation so phagocytosis microbes can’t be killed which means recurrent infections.

Question 27

What happens with Chediak higashi syndrome?

Answer 27

It cause a defective phagosome-lysosomes fusion this means the both can’t fuse together which result in a inability to kill phagocytosis microbes. This result I. Recurrent infection.

This is a rare genetic disease with a defective gene. The gene at fault is lysosomal trafficking regulator. This affects neutrophils to have defective phagocytosis which result in repetitive and severe infections.

Question 28

Describe chemotaxis of neutrophils?

Answer 28

First selected ligand roll into the selectin on endothelium at the inflamed site, then you have chemokines secreted at the endothelium which cause activation of integrins on neutrophils which attract it to the endothelium via integrin ligand which allows it to migrate into the tissue and go to the site of infection

Question 29

Example of an adhesion defect?

Answer 29

Leukocyte adhesion defect is caused by a defect in beta chain integrins which result in defective neutrophil chemotaxis. What happens was inability to adhere result in the inability to leave the blood vessel and do its job.

Question 30

What does toll like receptor do?

Answer 30

Toll like receptors recognise pathogens which rest on phagocytes, endothelial and epithelial cells. It can be located on either the surface of the cell or inside the cells. This located on top of the cell surface are there to detect extra cellular pathogens and those located inside the cells can defect microbial nucleus acids.

Question 31

Which TLR are on the cell surface?

Answer 31

TLR 1, 2, 4, 5 detect extra cellular pathogens.
TLR 1 detect bacterial lipoproteins
TR2 detect bacterial peptidoglycan
TLR4 detect lipopolysaccharide sin gram negative bacteria
TLR5 detect bacterial flagellin

Question 32

What are intracellular TLRs and what do they detect?

Answer 32

They are TLR 3, 7-9

They direct ssRNA, dsRNA, DNA viruses and bacterial DNA

Question 33

Those that are predisposed to infectious disease due to variation in toll like receptors, what are they?

Answer 33

They are termed polymorphism which are:

    - bacterial infection
    - asthma 
    - autoimmunity (lupus)