Innate

Question 1

Functions of neutrophils? Half life?

Answer 1

Phagocytosis
Releasing free radicals and proteases

1-2 days

Question 2

What are monocytes?

Answer 2

Kidney shaped nucleus
Invovled in antibody and complement assocaited phagocytosis of antigens

Question 3

What are macrophages derived?

Answer 3

Monocytes

Can also develop into dendritic cells

Question 4

What are functions of macrophages?

Answer 4

Phagocytose dead and damaged cells
Phagocytose opsonized (antibody or complement coated) antigens
SEcrete endogenous enzymes to digest the antigens
Engulf antigens and present them to T cells

Question 5

What are the most potent antigen presenting cells?

Answer 5

Dentritic cell

Present processed antigen on MHC class 2 molecules to naive T cells

Question 7

hat type of cell are mast cells?

Answer 7

Granulocyte

Found in vascularised connective tissues

Question 8

How to identify mast cells

Answer 8

Cytoplasmic granules that stain postiively with toluidine blue dye

Question 9

How does mast cell degranulation work?

Answer 9

IgE and IgG specific cell surface reeptors
Attach to the Ig
If adjacent receptor bound IgE or IgG cross-linked by antigen - degranulation - release contents of granules into extracellular space

Question 10

What are basophils?

Answer 10

GRanular cells that release histamine in response to inflammation

Question 11

How to identify eoisinophils?

Answer 11

Granulocytic leukocytes with cytoplasmic granules that stain bright orange by eosin.

Question 12

What is the function of eosinophils and how is this regulated?

Answer 12

When activated release free radicals and toxic granules - kill microbes and parasites but also cause damage to tissue

IL5 upregulates eosinophil production, produced by TH2 cells

Eosinophil must be activated by eotaxins (chemokines which attract and activate eosinophils)

Antigen must crosslink specific IgE that is bound to eosinophil

Question 13

What is the function of NK cells

Answer 13

Kill infected or malignant target cells

Decreased expression of MHC class I cells - trigger for NK cell lysis

Question 14

What chemokine is involved in trafficking innate cells by chemotaxis?

Answer 14

C5a from mast cells

Question 15

What are teh stages of cellular extravasation

Answer 15

Soluble cytokines (TNFa, IL1) secreted
Upregular expression of selectin ligand on endothelial cells
- Loose endothelial-neutrophil interation during rolling phase

Increase expression of adhesion molecules - neutrophils become loosely adhered to endothelium

Neutrophil becomes polarised and develops firm adhesion through integrin cell adhesion molecule interactions

Extravasation of leukocytes through endothelium mediated by PECAM-1 - disrupts intercellular tight junctions

Question 16

How do neutrophils kill pathogens?

Answer 16

Produce reactive oxygen intermediates and reactive nitrogen intermediates
- exposure to lysosomal granule contents

Question 17

What is complement?

Answer 17

Plasma proteins
Produced in liver and epithelial cells

Pro-enzymes until activated

Question 18

What are the actions of complement?

Answer 18

Activated complement proteins bind to pathogens and opsonize them

Small fragments cleaved off to act as chemoattractants

Membrane attack complex forms pores in baterial cells

Question 19

How can the complement cascade be initiated?

Answer 19

Classical pathway - binding of C1q to pathogen, bacteria and CRP complexes, bacteria and antibody complexes

Alternative pathway - spontaneously activated complement binds to pathogen surface

Lectin-binding pathway - complement binds directly to lectin

Question 20

What complements involed in membrane attack complex?

Answer 20

C5b to C9

Question 21

What detects pathogen bound IgG

Answer 21

Phagocytes with Fc receptors

Question 22

What detects pathogen bound C3b?

Answer 22

Phagocytes with CR1 receptors

Question 23

What can prevent phagocytosis?

Answer 23

Polysaccharide coated bacteria - unless opsonised