Innate Immunity 2

Question 1

How are humeral mechanisms regulated?

Answer 1

Humeral mechanisms are mediated by soluble Pattern Recognition Receptors which include;
Complement components
Lectins
Antimicrobial peptides and proteins

Question 2

Where do pathways of complement system converge ?

Answer 2

converge at the C3 component

Question 3

What does complement activation result in?

Answer 3

Opsonisation of microorganisms to promote facilitation of phagocytosis
Direct cytotoxic activity
Inflammatory response

Question 4

What are antimicrobial peptides?

Answer 4

Cationic and have an amphipathic structure
Strong ability to selectively bind to microbial plasma membranes and destroy integrity of microbial cell

Question 5

What are lectins?

Answer 5

Proteins which bind to carbohydrates
Highly specific for sugar groups present in other molecules so can cause agglutination of particular cells or precipitation of glycol-conjugates and polysaccharides.
Important in pattern recognition and pathogen elimination in innate immunity

Question 6

Give some examples of acute phase proteins

Answer 6

C-reactive proteins - opsonisation, bind to carbohydrates
Serum amyloid A - chemotactic to neutrophils and monocytes
Mannose binding lectin - complement activation
Ficolin - compliment activation

Question 7

What are some proteins and peptides involved in antimicrobial activity?

Answer 7

Lysozyme - muramidase or N-acetylmuramide glycanhydrolase, hydrolyses peptidoglycan, specific for Gram-positive bacteria
Lactoferrin - sequester free iron removing essential substrate required for bacterial growth
Lipocalin-2 (NGAL) - sequesters bacterial siderophores for iron, active only against Gram- negative bacteria