L19: Intracellular Immunity Flashcards
Where exactly can intracellular pathogens live inside the cell
Inside vesicles
Inside cytoplasm
Which pathogens are intracellular
Virus
Intracellular bacteria
Where are intracellular bacteria found inside the cell
In the cytoplasm
Or
In the vesicle
What type of cell can bacteria infect
Immune
Non immune
Which exact immune cell can bacteria invade
Macrophages
What is the advantage of the cell becoming invaded inside macrophages
They are shielded from the complement, antibodies and drugs
Which type of T cell kills intracellular bacteria that is inside the vesicles
CD4 TH1 cells
Which type of T cell deals with intracellular bacteria that is in the cytoplasm
CD8 T cell
What type of cell is a macrophage
Antigen presenting cell
Phagocyte
Usually what happens to a pathogen when it is phagocytosed by a macrophage
Pathogen is inside a phagosome
Phagsome fuses with lysosome
This forms a phagolysome
Pathogen is presented as a MHC class 2 complex on the macrophage
Which part of the phagocytosis part of the macrophage do vesicle restricted bacteria avoid
Fusing the phagosme with lysosome to form a phagolysome
If a bacteria is not Brocken down what does this mean in terms of presenting a MHC complex
MHC class 2 processing stops
How do bacteria become present in the cytoplasm if they are in phagosome at the beginning
They break out of the phagosome by cytolysins
What class of MHC class does cystolic pathogens present as
MHC class 1
If cystolic pathogens escape into the cytoplasm what does this mean in terms of presenting MHC 1 complex
Not presented and stops
How does the innate immunity kill intracelluar pathogen
Acidification Toxic oxygen derived products Toxic nitrogen oxides Antimicrobial peptides Enzymes Competitors
What type of T cell does the killing for vesicle/vacuole restricted pathogen
CD4 T cells because they present as MHC CLASS 2
How are TH1 cells activated
By dendritic cells that present MHC class 2
When the CD4 TH1 cell is activated what do they do
Recognise the complex of bacterial peptide with MCH class 2 and activate the macrophage
What happens to the activated macrophage that has the intracellular pathogen
Increase expression of MHC class CD40 Cd80 Amplification Fas expression for apoptosis Increase in TNF-alpha for apoptosis Reactive oxygen intermediaries Factors that promote acidification
Which T cell is involved in killing cystolic resident bacteria
CD8 T cell as the infected cell is presented with MHC class 1
How do CD8 T cells kill
They recognise the MHC class 2 and promote cell death
What is the most abundant intracellular infection in humans
Tuberculosis
Where exactly in the cell does tb live
Vacuole/vesicles
What are the clinical symtoms of TB
Breathlessness Chest pain Loss of appetite Coughing up blood Tiredness Persistent cough Loss of weight Night sweats
How does TB survive inside cell
Inhibit 3 key innate mechanisms of:
- reactive oxygen production
- reactive NO production
- prevent phagolysome formation
Which cell does TB infect
Macrophages
If TB is a vacuole restricted bacteria which T cell is involved in its killing
CD4 TH1 cells
How do CD4 TH1 cells help kill the bacteria
Activate the macrophage
What happens when the macrophage is activated
Phagolysosome is more efficient
Is the macrophage activation alone enough the kill the TB
NO
What happens to the infected macrophages
Have a granuloma forming that can kill macrophages
What can cause the spread of bacteria again
If the bacteria leak out the granuloma
How do we prevent TB
Vaccination of BCG
What happen when the granuloma collapses
Become casuesous ( mass of dead macrophages)
What are the factors that increase suspectibility to TB
HIV Malnutrition Close living Stress Diabetes Alcohol Immunosuppression
What type of genetic predisposition is likely to increase susceptibility to TB in patients
CD4 T cell defects
TH1 cytokine or receptor defects
