Dermatology Immunology Flashcards
What are the immune and non immune cells involved in the Epidermis?
Non immune: keratinocytes
Immune: Langerhans, T cells
What is the role of the keratinocytes cells in skin immunity?
- Sense pathogens and mediate immune response via cell surface receptors
- Can be activated by UV light and sensitisers (e.g. allergic contact dermatitis)
- Produce AMP (antibodies) that directly kill pathogen
- High AMP in psoriasis patients
- Produce cytokines and chemokines
In what condition is there a high AMP?
Psoriasis
What is the role of the langerhans cells in skin immunity?
- Act as sentinels (first line defence)
- Help to activate T cells by processing lipid Ag and microbial fragments and presenting them to effector T cells
- The antigen presenting granules are known as Birbeck Graules
What does TH1 and TH2 protect against?
TH1 protects against viral invaders
TH2 against parasitic invaders
Where are T cells produced?
- Produced in bone marrow
- Synthesised in thymus
Which conditions are associated with TH1 and TH2 cells?
TH1= psoriasis TH2= atopic dermatitis
Which conditions are associated with TH17?
Psoriasis and atopic dermatitis
What is the function of TH1 cells?
To activate macrophages, destroy micro-organisms
What is the function of TH2 cells?
Help B cells make antibodies
Where are CD4 and CD8 cells found in the skin?
CD4 and CD8 found in the dermis
CD8 in the epidermis
Why do histamines not always work?
There are numerous newly synthesised mediators
What cells are found at the dermis?
- Macrophages and neutrophils (though more abundant at site of infection)
- APCs (transmit info to B and T cells)
- Mast cells (effectors of IgE immune response)
- Dendritic cells- both dermal and plasmacytoid
What is the role of Dermal and Plasmacytoids?
- Both dendritic cells found in dermis
- Dermal is involved in antigen presentation and secretes chemokines and cytokines
- Plasmacytoid produces IFNalpha
Name some skin conditions associated with inappropriate immune response
-Psoriasis, Atopic Dermatitis, Bullous Pemphigoid, Contact dermaitis, systemic sclerosis, Urticaria, Systemic Lupus Erthyematous, Skin infections and tumours
What is the differences between class I and class II in the major histocompatibility complex?
Class I: found on all cells, present antigen to CD8, endogenous antigen
Class II: found on B cells, macrophages, more specific
Present to CD4 cells, exogenous antigen
What are the TH2 specialists in lymph nodes?
Langerhans cells
What is the most common trigger for psoriasis?
Psychosocial stress eg bereavement or due to infections
What is the hallmark of skin lesions in psoriasis?
Inflammation
Are psoriasis plaques irreversible?
Yes
When can psoriasis plaques occur?
After surgery as a late phase wound reaction
What is psoriasis triggered by?
Environmental factors in genetically susceptible individuals (risk factor genes)
What other medical conditions should be asked about in psoriasis?
-Gastritis, arthritis or may have an underlying infection acting as a trigger
What is the pathogenesis of psoriasis?
Keratinocytes under stress–>
Release factors that stimulate dendritic cells to produce IFN alpha–>
Release IL-IB/IL-6 and TNF–>
Dendritic cells are activated and migrate to skin draining lymph nodes–>
TH1 and TH17 activated–>
T cells attracted to dermis by cytokines–>
Keratinocytes proliferation stimulated, AMP released–>
Dermalfibroblasts involved, KC released
What IL is clinically relevant in psoriasis?
IL-17
What IL is clinically relevant in atopic eczema?
IL-4
What kind of reaction occurs in psoriasis?
Feed forward
What is fillagrin?
A protein which is chopped down by enzymes. The left over molecules work hydroscopically to maintain water retention in the skin, working as a natural skin moisturiser
What are filligrin mutations associated with?
Severe/early onset atopic eczema
What should you look at in eczema?
Hands, should be lots of lines
