Immunology of the respiratory system Flashcards
describe innate immunity
first line of defence, there when you are born
- No time lag
- Not antigen specific
- No memory
describe adaptive immunity
- Slower learnt responses to specific microbes
- Lag period
- Antigen specifc
- Development of membrane
what are antibodies
- These are plasma proteins that are made in the liver that are part of the immune system
what does IgA do
- mucosal areas such as the gut, respiratory tract and urogenital tract
- prevents colonization
- also in saliva tears and breast milk
what does IgD do
Functions mainly as anantigenreceptor on B cells that have not been exposed to antigens.
Shown to activate basophils andmast cellsto produce antimicrobial factors.
what does IgE do
Binds toallergensand triggers histaminerelease frommast cells and basophils, and is involved inallergy.
Protects againstparasitic worms
what does IgG do
Provides the majority of antibody-based immunity against invading pathogens.
what does IgM do
Expressed on the surface of B cells (monomer) and in a secreted form (pentamer) with very highavidity.
Eliminates pathogens in early stages of B cell-mediated (humoral) immunity before there is sufficient IgG.
what is the antibody that is largest in concentration
IgG
What antibody is produce first
IgM and then IgG
what type of MHC do all cells have
MHC1
what MHC is on APCs
MHC2
what do foreign epitopes on MHC2 sites do
- Foreign epitopes on MHC2 sites stimulate certain immune cells to manufacture antibodies that are specific to these epitopes. The antibodies bind to the original pathogens and help the immune cells recognize and attack the pathogens
what are the APC cells
dendritic and macrophages
describe what a multipotental haematopeitc stem cell develops into
- Multipotential haemotapoietic stem cell develops into a common myeloid progenitor
- Some leukocytes (white blood cells or WBCs) are granulated (they contain releasable granules)granulated white blood cells come from myeloblasts in the myeloid cells line the same one that produces erythrocytes
- Divide into megakaryocyte, erythrocyte, mast cell, myeloblast
what does a myeloblast divide into
- Myeloblast differentiated into the basophil, neutrophil, eosinophil, monocyte (develop into macrophages and dendritic cells )
what do monocytes differiate into
monocytes migrate out of the blood and differentiate into macrophages and dendritc cells
the more active neutrophils are the ..
- More active they are the more nuclei they have, neutrophils when they first differentiate have 3 or 4 lobes but when they are battling bacteria they become more activated and can have 6 or 7 lobes (HSN)
- Monocytes have kidney bean shaped nuclei
describe what macrophages do
- Macrophages are motile – they send out pseudopods and pull themselves along, the pseudopod attaches to the local tissue and this enables it to move
- Once they recognise the bacteria and start trying to engulf it not only do they display the epitote of the bacteira protein, they send out chemokines, which diffuse into the local capillaries and cause the attraction of other white blood cells to the site of infection in particular and initially neutrophils
where are monocytes formed
- Monocytes formed in the bone marrow spontaneously migrate out of the blood and into various different tissues
what happens when monocytes enter the target tissue
- they become lookout cells that identify and attack invading bacteria
where are macrophages found
- they are found in all tissues
- they are part of the mononuclear phagocyte
how do macrophages move around
amoeboid movement
how do. macrophages kill foreign particles
- Macrophages engulf and digest cellular debris, foreign substances, & microbes that they contact in a process called phagocytosis.
name some different types of macrophages
Alveolar macrophages move around inside alveoli and remove dust particles that have evaded the mucus lining the upper airways.
Osteoclasts are found in bone and remove debris from bone breakdown.
‘Histiocytes’ is a generic name for tissue resident macrophages.
Kupffer cells are in the liver, microglia in the brain, intestinal macrophages in the gut
what are toll like receptors
- TLR are on the pseudopods of the macrophages and these TLRs will bind to common antigenic surfaces on bacteria and fungi
- they are how it is known that something is foreign
how do macrophages use there toll like receptors
- Macrophages at rest send out long pseudopods projections with TLRs on the end
- These stick to any bacteria they touch if a bacterium is detected the pseudopod retracts and the bacterium is pulled back and engulphed in a phagosome
describe the process of phagocytosis
- there is chemotaxis and adherence of a microbe to a phagocyte this happens by use of the TLRs
- then the microbe is ingested by the phagocyte
- there is the formation of the phagosome which is the phagocytic vesicle
- then there is the fusion of the phagosome with a lysosome to form a phagolysosome
- digestion of the ingested microbe by enzymes
- formation of the residual body containing indigestible material
- discharge of waste materials
what are the roles of macrophages
- Antigen presentation
- Triggers an inflammatory response
- Phagocytosis
how has TB evolved to prevent phagocytosis
- Some bacteria have evolved defenses against the killing enzymes and free radicals in the phagolysosome.
- They have a waxy material in their cell wall that resists penetration by the lysosome enzymes.
- Macrophages phagocytose these bacteria but cannot kill them (fast enough) to stop bacterial replication
- the bacteria can actually grow (albeit slowly) inside the lysosomes!
what is found in the lungs of people with TB
Gohn focus
how is a Gohn focus formed
- In the centre of the cell is a mass of dead tissue called caseous necoriss that contains live TB bacteria
- Surrounding this is a layer of macrophages that have ingested the bacteria and are trying to kill them
- Reinforcements in the form of lymphocytes surround the macrophage to kill any bacteria escaping outwards
- Ring of fibroblasts on the outside
- Calcium gets deposits on the outer layers and therefore the Ghon focus can be seen on a chest x ray
what do some monocytes develop into
- Some monocytes develop into a specialised kind of macrophage called a dendritic cell
what tissues are dendritic cells found in
Dendritic cells are present in those tissues that are in contact with the external environment, such as the skin, inner lining of the nose, lungs, stomach and intestines
describe the structure of dendritic cells
- Dendritic cells have very extensive membrane processes which may be finger-like projections or folded into sheets. This means they have a very large surface area to expose Toll-Like Receptor