Immunology 3 Flashcards
What is the innate immune response?
Rapid response, lasts as long as the pathogen is present
Same generic biological response to many different pathogens
What is the adaptive immune response?
Slow response, response is unique to each individual pathogen, mediated by T and B lymphocytes, responsible for creating/generating immunological memory.
What cells are linked with the innate immune response?
Acute inflammation Macrophages Mast cells NK cells Neutrophils Complement
What cells are linked with the adaptive immune response?
B cells
T cells
Antibodies
Describe what happens in an acute limited infection?
There would be a normal immune response
Rapidly cleared by the immune system
Last immunological memory
Describe what would happen in a latent (chronic) infection?
The pathogen hides from the immune system
There are periodic episodes of pathogen reactivation and replication.
Describe what would happen in a chronic infection?
Failure to clear the pathogen
The immune response fails (immunodeficiency)
On-going pathogen replication
Describe what would happen if there was a defective INNATE immune system?
the level of microorganism would increase rapidly
Describe what would happen if there was a defective ADAPTIVE immune system?
There would be a slow increase of microoganism over time.
What are the two types of cell contact?
Direct contact
Indirect contact
Describe direct contact?
Direct receptor to ligand interaction
Describe indirect contact?
An injured tissue cell or activated immune cell can produce and secrete cytokines which go on to bind to other cells.
What are some physiological signs of actue inflammation?
Dilatation of small blood vessels -> increased blood flow, cell accumulation, increased cell metabolism (redness and head)
Increased permeability of post-capillary venues -> fluid accumulated in extravascular spaces (swelling)
Stimulation of nerve endings (pain)
Swelling and pain (loss of function)
What are the 3 phases of the innate immune system?
Recognition phase
Activation phase
Effector phase
Describe the Recognition phase?
- what do pathogens express?
Pathogen associated molecular patterns (PAMPs)
- these are not found on human cells
Describe the Recognition phase?
- what do innate immune cells express?
Pattern-recognition receptors (PRRs)
- these are the partner receptors for PAMPs
Describe the activation phase and effector phase?
Acute inflammation and pathogen killing
Describe the steps in the clearance of apoptotic cells by tissue resident macrophages?
- Apoptotic cells release ‘find-me’ signals to attract and activate macrophages
- Macrophages recognize specific ‘eat-me’ signals expressed on the surface of apoptotic cells
- Macrophages rearrange their cytoskeletal to internalize apoptotic cells
- Digestion of the ingested ‘cargo’
- Secretion of anti-inflammatory mediators (e.g. interleukin 10) to prevent tissue damage
Describe in more detail the steps in phagocytosis? (formation of phagosome etc)
- Receptor binding to ‘eat-me’ signals on apoptotic cell - formation of a phagocytic cup
- Cup extends around the target and pinches off, forming a phagosome
- Fusion with lysosomes to form a phagolysosome - degradation of contents (acidification, lysosomal hydrolases)
- Debris and antigens released into extracellular fluid
What happens is physical barriers are breached by pathogens?
Results in the activation of tissue resident innate immune cells by PAMPs (pathogens) and ‘danger’ signals (injured tissue cells)
Describe what happens when the early innate immune responses are triggered by pathogens (via PAMPs) and injured tissue cells (via danger signals)
Macropages, mast cells and NK cells cause the pathogen to be killed, the infected tissue to be killed and the production of inflammatory mediators.
What bacteria can evade phagolysosome killing?
Salmonella
Staph. aureus
Mycobacteria
Describe how macrophage activation can be enhanced?
Macrophage activation is enhanced by pro-inflammatory cytokines such as IFNγ (interferon gamma):
Describe how macrophage activation can be enhanced?
- what can this cause?
↑ production of toxic reactive oxygen and nitrogen species (ROS/RNS)
↑ antigen presentation capability of activated macrophages
