Basic Skin Immunology Flashcards
Name some structural factors that contribute to the skin’s immunological system
keratin layer, stratification
Name some cellular factors that contribute to the skin’s immunological system
immune system cells, keratinocytes, cytokines, chemokines, eicosanoids, antimicrobial peptides
What are the main differences between innate and adaptive immunity
INNATE- no memory
ADAPTIVE- memory
INNATE- non-specific
ADAPTIVE- v specific
How is the keratin layer formed
terminal differentiation of keratinocytes to corneocytes
Name some important structural proteins of the keratin layer and epidermis
Filaggrin, involucrin, keratin
Another name for the keratin layer?
Stratum corneum
How do keratinocytes protect the epidermis from pathogens?
SENSE pathogend via cell surface receptors, PRODUCE antimicrobial peptides (AMPs), cytokines and chemokines
Role of cytokines and chemokines?
Recruit and regulate cells of the adaptive and innate immune system
What happens in allergic contact dermatitis?
Keratinocytes are activated by a sensitiser eg soap. An immune response involving AMPs, cytokines and chemokines is then triggered
What are langerhans cells?
Dendritic cells that intersperse with keratinocytes in the epidermis. They are the main skin resident immune cell.
How do langerhans cells play a role in immune defence?
Present antigens to effector T cells in order to activate T cells
Main T cells found in epidermis
CD8+
Main T cells found in dermis
CD4+ and CD8+
Main T cells involved in psoriasis
CD4+ TH1 and TH17 cells
Main T cells involved in atopic dermatitis?
CD4+ TH2 and TH14 cells
What is CD4+ Th1 cells’ main role in immunity? What do they make?
Activate macrophages by producing cytokines IL-1 and IFNy
What is CD4+ Th2 cells’ main role in immunity? What do they make?
Help B cells to make Ab’s by producing cytokines IL4,5,6
What is CD8+ cells’ main role in immunity?
Kill infected cells directly; protect against viruses and cancer
Name the 2 types of dendritic cell in the dermis
Dermal DC and Plasmacytoid DC (pDC)
How do the 2 types of dendritic cell in the dermis differ?
Dermal- involved in antigen presentation and cyto/chemokine production
pDC- produce IFNa
What is the major histocompatibility complex or MHC?
Group of genes that code for proteins found on the surfaces of cells that help the immune system recognise foreign substances
Difference between MHC class 1 and 2?
1- on all cells, presents ENDOGENOUS Ag to CYTOTOXIC T cells
2- found on B cells and macrophages, present EXOGENOUS Ag to TH1 cells
Skin conditions associated with an inappropriate immune response
Psoriasis Atopic dermatitis Bullous pemphygoid Contact dermatitis Systemic sclerosis Urticaria SLE Skin cancer
Common side conditions of psoriasis
Arthritis and joint problems
What factors are known to trigger psoriasis?
bacterial pharyngitis, skin trauma, HIV infection, psychological stress, B blockers, lithium, genetics
What happens to keratinocytes when they are under stress?
Release factors that stimulate pDC to produce IFNa; Release IL1/6 and TNF
What happens to dendritic cells in psoriasis?
Are attracted by signals and migrate to skin draining lymph node to present to and activate T cells
What is the role of T cells in psoriasis?
Stimulate keratinocyte proliferation, AMP release and chemokines
Why is the skin barrier impaired in atopic eczema?
Less AMP in skin
Main antibody involved in Type 1 hypersensitivity
IgE
Main antibodies of type 2 and 3 hypersensitivity
IgG, IgM
Main antibodies of type 4 hypersensitivity
TH1 cells
When is the peak of a type 4 hypersensitivity reaction in terms of time
24-48h after contact with allergen
