Skin Immunology Flashcards
What are the differences between innaate and adaptive immunity?
innate is non-specific and has no memory whereas adaptive has memory and is highly specific
What is the keratin layer also known as?
the stratum corneum
what are 3 important structural proteins found in the keratin layer and epidermis?
filaggrin; involucrin and keratin
How do keratinocytes sense pathogens?
via cell surface receptors
What do keratinocytes produce that can directly kill pathogens?
antimicrobial peptides (AMPs)
What is the main skin resident immune cell?
Langerhan cells
What cell do Langerhan cells present antigen fragments to?
effector T cells
What type of T cell is found in the epidermis mainly?
CD8+ T cells
What T cells are found in the dermis?
both CD4+ and CD8+ as well as NK cells
What types of helper T cell are associated with psoriasis?
Th1 and Th17
What types of helper T cell is associated with atopic dermatitis?
Th2 and Th17
What is the difference between Th1 and Th2?
Th1 activate macrophages to destroy micoorganisms whereas Th2 help B cells to make Ab. Thye produce different cytokines
What are CD8+ important for protection against?
viruses and cancer
Where are T cells sensitised?
thymus (hence the name)
What are the types of dendritic cell found in the dermis?
dermal DC and plasmacytoid DC
What are the dermal DCs involved in?
Ag presenting and secreting cyto/chemokines
what do plasmacytoid DCs do?
produces IFNa
What chromosome contains the gene for MHC?
chromosome 6
What is the difference between MHC class 1 and 2?
Class 1 is found on almost all cells and presents endogenous Ag to CD8+. Class 2 is found on APC and presents exogenous Ag to helper T cells
Descrivbe the immunopathogenesis of psoriasis.
Keratinocytes undergo stress which causes them to release factors stimulating the plasmacytoids to present to Th1 nad Th17 helper T cels. T cells are attracted to dermis by chemokines and there stimulate KC proliferation, AMP release and neutrophil- attracting chemokines. Dermal fibroblasts then become involved and release KC and epidermal growth factors.
What does filaggrin do?
mother natures moisturiser- holds onto water molecules
How is filaggrin involved in atopic eczema?
mutations in the filggrin gene is associated with sever/early onset disease
In atopic eczema there is a defective skin barrier, what does this lead to?
access/sensitisation to allergen and promotes colonisation by microbes
What is type 2 hypersensitivity?
cytotoxic mediated. IgM or IgG antibody binds to cell surface antigen.
What is type 3 hypersensitivity?
immune complex mediated. immune complexes are despoited in small vessels activating complement etc.
What investigations are done for allergies?
spefici IgE; skin prick; challenge test; serum mast cell tryptase level (only during anaphylaxis)
When is a challenge test done?
Only if the skin prick test in negative
What type of hypersensitvity is allergic contact dermatitis caused by>
type 4
What is irritant contact dermatitis?
contact with agents that abrade, irritate and traumatize the skin directly. Non-immunological process
