The Immune Response Flashcards
Following pathogen enrty, what does tissue resident cells bind to?
Pathogens
What happens after tissue resident cells bind to pathogens?
Cell signalling and the release of proinflammatory mediatord and chemokines
How do tissue resident macrophage recognise a pathogen?
Pattern recognition receptors (PRR) and macrophages bind to pathogen associated molecular patterns (PAMPs) on pathogens
Where are pattern recognition receptors found?
On other innate immune cells
What are the different cellular compartments are pattern recognition receptors found?
Cell surface for extracellular pathogens
Cytoplasmic for pathogens that have entered cells
Endosomal vesicles following cell entry
What is the result of the binding pathogens to pattern recognition receptors?
Signalling and immune cell activation
What does the binding of Toll-like receptors result in?
Gene transcription and the release of pro-inflammatory signalling molecules
What is the earliest stage of inflammation?
Recognition of a pthogen by macrophages and dentric cells in tissues
What gets afftected when soluble signalling molecules are released?
Local blood vessels
What happend to the blood vessels when inflammation occurs?
The blood vessels dialate and express adhesion molecules which bind cells in the blood
When tissue resident macrophages and dentric cells express new molecules, what is the role of the new molecules?
To start the adaptive response
What is the result of cytokines released by tissue resident macrophage?
Changes to blood flow and permeability of vessel
What increases movement of plasms proteins and leucocytes out of circulation?
Cytokines released by tissue resident macrophage
What causes leucocyte influx into tissues?
Changes in blood flow and vascular permeability
What are phagocytic cells?
Neutrophils and macrophages
Movement into tissue cells is a multistep process helped by what?
cytokines, chemokines and adhesion molecules
What are the two major families of adhesion molecules?
Integrins and selectins
Where to leucocytes move once they have ‘stopped’?
Through the vessel wall through postcapillary venules
What stimulates when chemokines act on the adhered leucocytes?
Their migration
What and where do extravasated leucocytes follow?
Chemokine gradients to the site of infection
What are endogenous?
Chemokines, complement fragments
What are exogenous?
Bacterial products
What happens in the first 6-24hrs of inflammation?
Accute inflammation, neutrophils predominate
What replaces neutrophils after 24-48hrs?
Monocytes
Why are neutrophils first?
They are most abundant leucocyte in blood
Rapidly respond to chemokines
Bind to adhesion molecules more tightly
What is the lifespan of neutrophils?
24-48hrs
Do monocytes live longer then neutrophiles?
Yes
Do monocytes divide and dominate in prolonged inflammation?
Yes
Why do we recriut cells to the dite of infection?
Pathogens at the dite of infection are recognised by phagotic cells recruited from the circulation
The recognition induces phagocytosis and intracellular killing
PRR’s on phagocytes bind to pathogen associated molecule patterns on bacteria
What does phagocytosi require?
Recognition and binding
Engulfment
Killing
What are the three steps of adaptive immunity?
- Specialised peripheral lymphoid tissues concentrate antigens from portals of entry
- Naive lymphocytes migrating through peripheral lymphoid tissues recognise antigens and intitate the adaptive response
- Effector and memory lymphocytes circulating in the blood and home to peripheral sites
What is the funtion of lymphocytes?
Can specifically recognise and ditinguish different antigenic determinants?
What do lymphocytes consist of?
Distinctive subsets with different functions although they look the same
What do B-lymphocytes produce?
Antibodies
What to T-lymphocytes produce?
CD8+ or CD4+
Do B and T cells have antigen receptors?
Yes BCR and TCR
What are B and T cell antigen receptors generated by?
DNA recombination
How are lymphocytes developed?
After birth, all blood cells, including lymphocytes are generated from stem cells in the bone marrow
What happens when naive lymphocytes enter secondary lymphoid tissues and encounter entigen?
They become activated
Is there a large or small population of naive lymphocyted that recognise a specific antigen?
A small population
What does it mean for a naive lymphocytes to recognise a specific antigen?
Clonal selection
what does activation of naive lymphocytes result in?
The proliferation and differentiation into armed effecot and memory cells
Where do armed effectors migrate to?
The site of infection
