Immunology Flashcards
how is the keratin layer formed?
through terminal differentiation of keratinocytes to corneocytes
name some important structural proteins in the keratin layer & epidermis
filaggrin
involucrin
keratin
name some features of the keratin layer
tough
lipid rich
physical barrier
what do keratinocytes do in the epidermis?
sense pathogens via cell surface receptors and help mediate an immune response
what can keratinocytes be activated in the epidermis?
UV light
sensitzers e.g. allergic contact dermatitis
what do keratinocytes produce in response to pathogens?
antimicrobial peptides (AMPs)
cytokines
chemokines
what are Langerhans cells?
a type of dendritic cell that intersperse with keratinocytes in the epidermis
what are Langerhans cells characterised by?
the birbeck granule
what do Langerhans cells do?
process lipid Ag & microbial fragments & present them to effector T cells to activate them
what type of T cells are found in the skin?
mainly CD8+ in the epidermis
CD4+ & CD8+ in the dermis
subsets (NK cells) are also found
which CD4+ Th cells are associate with inflammation?
Th1 - psoriasis
Th2 - atopic dermatitis
Th17 - atopic dermatitis & psoraisis
where are T cells produced?
bone marrow
where are T cells sensitised?
thymus
how are Ags recognised and T cells activated?
using the T cell receptor (TCr) & major histocompatibility complex (MHC)
enhanced by co-recptors
what do Th1 cells do?
activate macrophges to destroy macrophages using IL2 & IFN gamma
when are Th1 cells especially useful?
against viral invaders
what do Th2 cells to?
help B cells to make Ab using IL4, IL5 & IL6
when are Th2 cells especially useful?
against parasitic invaders
when are CD8+ cells useful?
important in the protection against viruses & cancer
which types of dendritic cell are found in the dermis?
dermal dendritic cell & plasmacytoid dendritic cell
what do dermal DCs do?
involved in Ag presenting & secreting cytokines & chemokines
what do plasmacytoid DCs do?
produce IFN alpha
when are plasmacytoid DCs found in the skin?
they are low or absent in normal skin but found in relatively high numbers in diseased skin
what is psoriasis?
an over-reaction of the immune response presenting as chronic inflammation, specifically a non-late phase wound response
describe the immunopathogeneis of psorasis
keratinocytes under stress release factors that stimulate pDC to produce IFN alpha, interleukins& TNF which activate DC which migrate to lymph nodes to present to & activate Th cells
T cells then attracted to dermis by cheekiness & secrete interleukins
what is the key factor in atopic eczema?
impairment of the skin barrier function due to mutations in the filaggrin gene and decreased AMP in skin
how does impairment of the skin barrier function cause atopic eczema?
allows access/sensitisation to allergen & promotes colonisation by micro-organisms