Immunology Flashcards
what are the chemical signals/ molecules in the skin that influence cell behaviour or help target pathogen
cytokines, chemokines, eicosanoids, antimicrobial peptides
what is an antigen
any chemical structure (usually a protein/peptide) that can illicit an immune response via an antibody or t cell
what is hypersensitivity
overreaction to an antigen
what is autoimmunity
reaction to host tissue- chronic inflammation
what forms the keratin layer
terminal differential of keratinocytes to corneocytes
name three important structural proteins in the keratin layer and epidermis
filaggrin
involucrin
keratin
what is the stratum corneum
a.k.a keratin layer
what are the 3 main roles of keratinocytes in the epidermis
sense pathogens via cell surface receptors and help mediate an immune repsonse
produce antimicrobial peptides (AMPs) that directly kill pathogens
produce cytokines and chemokines
what can activate keratinocytes
UV and sensitisers (e.g. allergic contac dermatitis)
what are langerhans cells and where are they in the skin
a dendritic cell (the main skin immune cell) that is interspersed with keratinocytes in the epidermis
name the antigen presenting cell in the cell that has birbeck granules
antigen presenting cells
what is the role of langerhans
process lipid Ag and microbial fragments and present them to effector T cells- helping to activate them
where in the skin are CD8+T cells mostly found
in the epidermis
where in the skin are CD4+T and CD8+T found
dermis
what inflammation condition is associated with the CD4+TH cell TH1
psoriasis
what inflammation condition is associated with the CD4+TH cell TH2
atopic dermatitis
what inflammation condition is associated with the CD4+TH cell TH17
psoriasis and atopic dermatitis
where are t cells produced and matured (sensitised)
bone marrow
thymus
what are t cells the basis of
cell mediated immunity
what is the role of CD4+T cells and the roles of the different types
helper t cells- release chemical mediators or signalling molecules such as interleukins and interferons
TH1 activate macrophages to destroy microorganisms (IL2 and IFNy)
TH2 help B cells to make Ab (IL4, IL5, IL6)
what is the role of CD8+T cells
cytotoxic T cells- can kill infected cells, viruses and cancer cells directly
what connects triggers the immune response when it can not be made
connection between cells to recognise each other involving MHC
what are the different types of dendritic cells found in the dermis and their role
dermal DC- Ag presetation and secretion of cyto/chemokines
plasmacytoid DC- produce IFNa, found in diseased skin
what is the role of dendritic cells
antigen presenting cells
transmit information to T and B cells
secrete cyto/chemokines during the inflammatory immune response
why would neutrophils be in the skin
as circulating leukocytes (neutrophils, basophils, eosinophils) are attracted to tissue by chemokines
what is the role of mast cells in the skin
effectors of IgE mediated immune response (allergy), when activated release inflammatory mediators
what are the preformed inflammation mediators released by mast cells
TNF, tryptase, chymase, histamine
what else can activate mast cells
physical trauma, drugs, micro-organisms
what chromosome encodes MHC
chromosome 6
what is the role of MCH1 and where is it found
on almost all cells
present Ag to cytotoxic T cells
present endogenous Ag
what is the role of MHC2 and where is it foun
found on antigen presenting cells (B cells, macrophages)
present to TH cells
present exogenous AG
(1= present to cytotoxic 2= present to TH cells)
are NK cells in the dermis
yes
what causes psoriasis
environmental factors (bacterial pharyngitis, mild trauma of skin, HIV, stress, B blockers, ingestion of lithium) in genetically susceptible individuals
who is most likely to get atopic eczema
children
what is the cause of atopic eczema
genetic and environmental factors= impairment of barrier function
- mutatino in fillagrin gene
- decreased AMP in skin
immune cells actracted to stressed KC, like in psoriasis
defective barrier allows access/sensitisation to allergen- promotes colonisation
name 3 autoimmune skin conditions
psoriasis, vitiligo, systemic lupus erythematosus
what causes skin problems with lupus
faulty apoptosis causes DNA and antigens to accumulate resulting in antibodies against own DNA
what are causes of secondary immunodeficiency
AIDs, malignancy, aging, diabetes, renal malfunction, burns, alcoholic cirrhosis, malnutrition, obesity
what mediates type 1 hypersensitivity
IgE
describe the process of allergies
early exposure to allergen causes production of IgE which binds to FCER1 on mast cells. later exposure causes rapid crosslinking of receptors, signal transduction and degranulation of the mast cells
what mediates type 2 and 3 hypersensitivity
IgG and IgM
what mediates type 4 hypersensitivity
TH1 cells
what hypersensitivity reaction is important in autoimmunity and transplantation
type 2
what is an arthus reaction
type 3 hypersensitivity reaction (slower than type 1 but faster than type 4)
which hypersensitivity reaction is delayed, give examples
type 4; contact allergy
