32. Intro to the immune system 1 and 2 Flashcards
what are the 2 types of overreactions of the immune system
autoimmunity - Type 1 Diabetes, rheumatoid arthritis, MS, IDB
Allergic reactions- eczema, hay fever, asthma
what are 2 types of immune under reaction
Cancer - HIV, EBV, HCV
name some ways a pathogen can enter the body
digestive system, respiratory system, urogenital system
skin damage
what is the physical barrier of infection
skin
what makes the skin a good barrier
- Physical barrier - tightly packed, highly keratinized cells
- Physiological factors
- Low pH (5.5)
- Low oxygen tension
- Sebaceous glands – hydrophobic oils, lysozymes, ammonia
what does mucus line
all the body’s cavities that are in contact with the external environment
what antibody is in mucus
secretory IgA
what are the three barriers to infection
skin, mucus, commensal bacteria
define the innate immune response
Innate immunity is present continuously, it is a defence mechanism that is present from birth.
The same generic response occurs to many different microbial species.
define the acquired (adaptive) immune response
Acquired (adaptive) immunity is (usually) induced by the presence of ‘foreign’ or non-self-materials.
A unique response is generated to each individual pathogen
which out of innate and acquired has immunological memory and a lag time from exposure to response and is specific
adaptive/acquired
cytokines - interferons- are released from virally infected cells to signal neighbor cells. what does this cause
it destroys RNA and reduce protein synthesis
undergo apoptosis
activate immune cells such as NK cells
describe macrophages
phagocytose bacteria
release pro inflammatory mediators TNFa
describe phagocytosis
- PRRs on macrophages bind to PAMPs on pathogen, which signals the formation of the phagocytic cup
- Cup extends around the pathogen and pinches off – phagosome
- Phagosome fuses with lysosome – phagolysosome
- Pathogen killed and contents degraded
- Debris released into extracellular fluid
macrophages express ………. and they release……….
MCH-II
TNFa
what do mast cells do
deal with pathogens too big for phagocytes
mast cells release histamine, tryptase, TNF, Chemokines, leukotrienes, prostoglandins
associated with allergy
describe neutrophils in innate immunology
Transendothelial migration is the recruitment of neutrophils to the site of infection during acute inflammation:
- slower blood flow, allowing neutrophils to undergo margination
- Neutrophils travel close to endothelial cells instead of centre of the vessel
- Neutrophils can then encounter and bind to adhesion molecules expressed by the endothelial cells (e.g. selectins, ICAM-1)
- Neutrophils migrate across the endothelium via diapedesis
- Once in the tissues, the neutrophils travel to the exact site of injury via chemotaxis
- Neutrophils are then activated by PAMPs and pro-inflammatory mediators such as TNF⍺
Neutrophils can then encounter and bind to adhesion molecules expressed by the endothelial cells such as
selectins, ICAM-1
. Neutrophils migrate across the endothelium. what is this process called
diapedesis
Once in the tissues, the neutrophils travel to the exact site of injury what is this process called
chemotaxis
Neutrophils are then activated by PAMPs and pro-inflammatory mediators such as
TNF⍺
what does TNFa stand for
Tumour Necrosis Factor alpha
what does PRR stand for
Pattern Recognition Receptors
what does PAMPs stand for
Pathogen associated molecular patterns
what are the 3 ways neutrophils kill
phagocytosis, degranulation (release of anti-bacterial granules), NETS (net like structure that traps pathogens leading to phagocytosis)
what are the 3 modes of ingestion by neutrophils
Phagocytosis
Endocytosis - molecules bound to membrane receptors are internalized
pinocytosis - ingestion of fluid of surrounding cells
lysosomes contain what
hydrolytic enzymes
when the phacocytic cup pinches off it creates a
phagosome
what fuses with the phagosome
lysosome
when the phagosome and lysosome combine it creates a
phagolysosome
what are the 3 antigen presenting cells
dendrites, macrophages, B cells
what is pinocytosis
ingestion of fluid of surrounding cells
what are NK cells
Natural Killer Cells
what do NK cells release to kill by degranulation
perforin
NK cells respond to what class of presenting cells
MHC class I - virally infected and cancerous cells
what else do NK cells produce
IFNy
macrophages express its antigens through…..
MHC-II
dead and dying neutrophils produce what
pus
MHC- II can only be found on….
antigen presenting cells aka dendrites, macrophages and B cells
which cells present MHC-I
all nucleated cells in the body
Basophils granules contain what
histamine
eosinophils are associated with what
allergy
Basophils act as effector cells in what reaction
allergic reactions
what is the complement system
activated in response to inflammation and creates a chemical cascade of chemical reactions
where are the complement proteins produced
liver
what are the 3 pathways for the complement system
Classical
Mannose Binding Lectin
Alternative
take me through the complement system
- C3 is cleaved as it is an inactive precurser
- Cleaved into c3a and c3b.
- Active c3b associates with another compliment system protein to produce C5 convertase
- This causes cleavage of C5 into C5a and C5b
- Active C5b produces a pore-forming channel which is inserted into the cell wall which causes Cell death. This is called MAC
what is the alternative pathway in the complement system
after C3 cleaved into C3a and C3b, C3b can then amplify the reaction via the alternative pathway, causing more C3 to cleave into C3a and C3b
what are C3a and C5a responsible for
acute inflammation (they are anaphylatoxins)
what is MAC
membrane attack complex
what is the classical complement system path initiated by
IgM and IgG/ CRP
dendrites are MCH-???? beacuse they are ……………
MHC-II beacuse they are antigen presenting
what activates complement via MBL pathway
mannose-binding lectin
what is opsonisation
when a pathogen is marked for phagocytosis by being bound by an antibody
what else does C3b also do besides become C5
opsonisation - leading to phagocytosis
IgG can act as an
opsinin
name some opsinins
- C3b
- C-reactive protein (CRP)
- IgG / IgM antibodies
