Lec 1, 2 Flashcards
What are some mechanical barriers to infection?
- Epithelial cells joined by tight junctions
- Longitudinal flow of air or fluid
- Movement of mucus by cilia
- Tears
- Nasal cilia
What are some chemical barriers to infection?
- Fatty acids
- beta defensins
- Lamellar bodies
- Cathelicidin
- Low pH
- Enzymes (pepsin)
- alpha defensins
- Pulmonary surfactant
- Enzymes in tears and saliva (lysozyme)
- Histatins
What is the activated function of a macrophage
Phagocytosis and activation of bactericidal mechanisms.
Antigen presentation.
Receptors of the innate immune system
- Toll like receptors
- complement receptor
- lipid receptor
- scavenger receptor- bind LDL, bacteria/ yeast
- beta- glucan receptor- C-type lectin receptor, anti fungal receptor
mannose receptor- bind carbohydrates
What family of receptors are toll-like receptors and what do they recognise?
They are a family of Pattern recognition receptors and they recognise PAMPS and DAMPS (from damages cells)
Examples of other PRRs and damage receptors
NLR= NOD like receptors: recognise damage and initiate the inflammsome for caspase-1 activation and cell death.
RLR= RIG like receptors: recognise viruses
C-type lectin receptors: recognise fungi and worms.
Cytokine families and their functions
- Interleukins- diverse
- Interferons- anti viral
- Colony stimulation factors- haematopoesis
- Tumour necrosis factor- inflammation
- Chemokines- chemotaxis
Endocrine, paracrine and autocrine definitions
Endocrine- acts from a distance
Paracrine- acts nearby
Autocrine- acts on itself
Immediate and delayed mast cell products
Immediate -Histamine -Heparin -Enzymes Delayed -Prostaglandins -Leukotrienes -Cytokines
Role of interleukins in the liver and brain
Liver- IL6 stimulates liver hepatocytes to make acute phase proteins
Brain- IL1 promotes fever, anorexia, somnolence.
If local cytokine response is high enough then cytokines become systemic and go to other organs.
Initial acute phase proteins and their role
Fibrinogen- clotting
Haptoglobulin- binds iron
Complement C3 cleaved to make C3a- activate mast cells and C3b an opsonin
Mannose binding protein- opsonin
Later acute phase proteins and their role
Serum amyloid- inhibits fever and platelet activation
C-reactive protein- binds phosphoryl choline, opsonin
What is an opsonin?
‘come eat me’ signal
pathogen=digestive biscuit
opsonin covered pathogen= chocolate biscuit
Opsonins of the innate immune system examples
C-reactive protein
Mannose binding protein
C3b
Interferon types and their functions
IFN alpha, beta and gamma
- Inhibit viral replication
- Bind to receptors on other cells and make cells resistant to infection
- activate macrophages and NK cells
