23 - Skin Inflammation Flashcards
Cardinal signs of inflammatin
Heat
Redness
Swelling
Pain
Langerhans cells
In the epidermis
Dendritic cells - spine like projections
Pick up antigens that enter the skin and transport to the lymph nodes
What type of sensitivity is Mast Cell Mediated Inflammation
Type 1 hypersensitivity
What are the steps in Mast Cell mediated inflammation
1) Allergen ingested by APCs which present to allergen to cells
2) TH2 T cells recognise and produce 1L-4
3) IL-4 promotes B-cells –> plasma cells
4) Plasma cells release IgE antibodies
5) IgE antibodies bind to Fc receptor on mast cell
6) 2nd exposure - allergen binds to IgE
7) Mast cell degranulates when all binds
What is released from a mast cell in mast cell degranulation
Histamines Cytokines Enzymes Prostaglandins Leukotrienes
Function of histamine
Smooth muscle contraction
Bronchoconstriction
Intestinal hypermotility
Arteriole dilation - hypotension + headache
What is Der P1
Enzyme allergen from faecal pellets of dust mites
Breaks down the components of tight junctions
What is mast cell degranulation responsible for
Urticaria
Asthma
Hay fever
What causes anaphylaxis
Antigen into blood stream
binds to IgE on basophils
Release of inflammatory mediators
Bronchospasm and circulatory collapse
What is omalizumab
Treatment for resistant urticaria and asthma
MoA of omalizumab
Binds to circulating IgE to decrease cell bound IgE
Decreases expression of high affinity receptors
Decreases tissue infiltration + mediator release
What type of sensitivity is antibody mediated inflammation
T2 hypersensitivity
where antibodies bind to bodies own tissues
What is the mechanism of antibody mediated inflammation in pemphigus vulgaris
Antibodies are formed against desmosomes
Lack of cohesion between keratinocytes and epidermiss
How do you treat pemphigus Vulgaris
Oral steroids
MoA of Rituximab
Targets CD20 on B cells
What type of sensitivity is immune complex mediated
Type 3 hypersensitivity
How does immune complex mediated work
1) Accumulation of immune complexes (antigen-antibody) that havent been cleared
2) Gives rise to inflammatory response and leukocyte accumulation
Where do the immune complexes insert themselves (in type 3 hs)
Blood vessels
Joints
- this causes symptoms
Symptoms of early vasculitis
Erythema + oedema
Symptoms of established vasculitis
Palpable purpura
Severe vasculitis
Ulceration + necrosis
What antingen and antibody complex in SLE
DNA
Anti DNA
What antigen and antibody complex in Polyarteritis Nodosa
HbsAg
Anti-HBsAb
Type of sensitivity is Delayed hypersensitivity
Type 4 hypersensitivity
What is the pathophysiology of Allergic Contact Dermatitis
1) Contact allergens can cross the stratum corneum + form a conjugate with a protein
2) Conjugate recognised by langerhans cells as foreign
3) Transported to lymph nodes
4) if meet the allergen again - allergic reaction
What is the role of IL-2 and IFN-gamma in ACD
Promote Th1 response- secrease IL2, IL3, GM-CSF, IFN and TNF
Promotes macrophage response
Causes inflammation
Examples of contact allergens
Nickel
rubber
topical antibiotics
What is granuloma formation
Collection of macrophages (aka histiocytes)
Causes of granuloma formation
TB
Sarcoidosis
foreign body granuloma
