Skin Inflammation Flashcards
what are the cardinal signs of acute inflammation
- heat - caused by increased blood flow and vessel dilation
- redness - caused by increased blood flow and vessel dilation
- swelling - accumulation of fluid
- pain - pressure on nerve endings
- loss of function
What cells are found in skin during inflammation
Neutrophil Eosinophil Lymphocyte Plasma cell Macrophage Mast cell
where is the langerhans cells
In the epidermis
Dendritic cell- spine-like projections
what are langerhan cells used for
Efficient at presenting antigen to CD4+ helper T-cell
Pick up antigens that enter the skin and transport them to the lymph node
what are the different types of inflammation in the skin
(type 1)Mast cell mediated - urticaria
(type 2)Antibody mediated - pemphigus
(type 3) Immune complex mediated - vasculitis
(type 4) Delayed hypersensitivity - contact allergic dermatitis
(type 5)Granuloma formation - TB, sarcoidosis
describe what happens in mast cell mediated immunity
When an antigen is inhaled and comes in through the skin it is picked up by the APC and then presented to the T cell
In mast cell mediated immunity th2 cells produce IL-4, IL-5,
- Eosinophils – release granules
- B cells produce IgE which binds to mast cells and causes degranulation
Mast cell degranulation
- Released mediators such as histamine, leukotrienes, prostaglandins, platelet aggregating
what can cause mast cell degranulation
- Drugs- aspirin, NSAID
- Serum factors
- Insect sting
- Nuts
- Shell-fish
- House-dust mite
What are the effects of the mast cell degranulation on cellular components
Lipid mediators
- recruitment and activation of monocytes and macrophages
- migration and activation of dendritic cells
things such as histamine, heparin, proteases
- recruitment and activation of T cells
- recruitment and activation of neutrophils, basophils and eosinophils
- phagocytosis
- degradation of endogenous toxic mediators
Cytokines
- degradation of snake venom components
what does - histamines and lipid mediators do - cytokines and lipid mediators - Enzymes do
- histamines and lipid mediators do = vascular leak and bronchoconstriction, intestinal hyper motility
- cytokines and lipid mediators = inflammation
- Enzymes = tissue remodelling
What is the central role of histamine
bronchospasm
stimulates sensory nerves; itchy flare
smooth muscle contraction; vessel leakage and oedema
arteriole dilation; headache and hypotension
modulation of immune response via H2 receptors
what is an example of an allergen
Der P1 is an enzyme allergen
from the faecal pellets
of the dust mite
describe the Der P1 allergen
- easily aerosolized and inhaled.
- Der P1 breaks down components of tight junctions
which helps it to cross mucosa.
what are the local signs of a type I reaction
urticaria
asthma
hay fever
what is anaphylaxis
Generalised type I
- antigen released into blood stream, binds to IgE on basophils- massive release of inflammatory mediators- bronchospasm and circulatory collapse- known as ANAPHYLAXIS
What is the new treatment for resistant urticaria and asthma
omalizumab - binds to IgE and reduces expression of receptors
What is a risk factor for anaphylaxis
being an asthmatic
describe the antibody mediated inflammation
Completed mediated lysis – completed antibody and antigen that is pahgocytosised by an extravascular macropahegs which causes antibody dependent cell mediated cytoxicity and receptor blockage
What happens in pemphigus vulgarisms
- affects the desmoglein-3
- patients develops antibodies to the desmosome and the cells breakout
- you get acantholysis
what sign do you get in pemphigus vulgarisms
positive Nikolsky sign
- rub a red area of the skin and the skin comes of
- can also get nasty blistering in the mouth
What is acantholysis
loss of cohesion
between epidermal keratinocytes
What does the histology of pemphigus vulgarisms look like
– loss of cohesion between the epidermal keratinocytes
-
what happens in diluted pemphigus vulgaris serum
Diluted pemphigus vulgaris serum binds to normal epidermis at intercellular junctions (where desmogleins are localised)
What is the treatment of pempgius vulgaris
Oral steroids
Immunosuppresion c mycophenolate mofetil or azathioprine
Rituximab (targeting CD20 on B cells)
describe immune complex mediated vasculitis
- Get antibody forming an immune complex
- This results in blood vessel reduction of complement
- Aggravation of platelets
- antigen antibody complexes binding to antibodies
- Lysis of enzymes
- This results in a leaky vessel
