Flashcards in HOST DEFENCE Deck (29)
what are the non-immune host defence mechanisms in the lungs?
coughing - some voluntary control
sneezing - involuntary
multipotent basal cell population - can differentiate into different cell types if damage occurs
what system is used to classify hypersensitivity?
gell and coombs hypersensitivity classification
what is type 1 hypersensitivity?
allergy, anaphylaxis and atopy
IgE causes release of histamines from mast cells by activating FceR1 receptors
causes vasodilation and opening of gap junctions
how is type 1 hypersensitivity diagnosed?
via skin prick test
radio-immunosorbent assay (RAST)
how is type 1 hypersensitivity treated?
what is type 2 hypersensitivity?
IgG binding to self antigens (autoimmune)
attacks own body's cells
give an example of type 2 hypersensitivity?
IgG is raised due to type IV collagen
this leads to glomerulonephritis and pulmonary haemorrhage
what is type 3 hypersensitivity?
immune complex diseases
large scale immune response leading to complexes of IgG precipitating - are unable to be cleared by macrophages
give examples of type 3 hypersensitivity
pigeon fanciers lung
malt worker's lung
give an example of type 1 hypersensitivity?
what is type 4 hypersensitivity?
delayed type hypersensitivity reaction
T-helper cells form granulomas around pathogens with macrophages in a cell mediated response
does not involve antibodies
give examples of type 4 hypersensitivity
what is the innate immune system?
the immune system you are born with
comprised of specialist macrophages and neutrophils
what are the specialist macrophages of the innate immune system?
they initate acute inflammation via cytokines and antigen presenting via MHC II
what are primary granules found in neutrophils?
contain myeloperoxidase, elastase, cathespins, defensins
what are the secondary granules found in neutrophils?
receptors, lysozymes and collagenase
how do neutrophils work?
they carry out bacterial killing through enzyme release and generation of ROS by NADPH oxidase complex
what is the adaptive immune system mediated by?
B and T lymphocytes
how are lymphocytes activated?
through receptor binding to epitopes of antigens on pathogen surface, free antigens in plasma or through peptides presented via MHCs
how is the variable region of antibody receptors generated?
by VDJ gene recombination
what is affinity maturation?
it is the process by which antibodies with a higher affinity for antigen are more favourably selected
what is the role of Treg cells?
they are responsible for removal of cells that have receptors capable of binding self-antigens - immune tolerance
how does immune memory work?
primary immune response is low level, but further exposure produces larger responses as more memory cells are produced which have higher affinity receptors and antibodies
what is the role of B cells?
they mature into plasma cells which produce antibodies M-G
what happens in B-2 integrin deficiency?
CD18 marker not expressed on neutrophil surface
it is unable to move out of endothelium to infected tissue
this causes deep recurrent infections
what happens in acutre respiratory distress syndrome (ARDS)?
respiratory distress due to widespread inflammation
leads to respiratory failure, non-cardiogenic oedema and multi-organ failure
what happens in goblet cell metaplasia?
pathogenic plasticity of airways in smokers due to basal cell differentiation
what is anti-neutrophil cytoplasmic antibodies?
an autoimmune reaction causing vasculitis