Immunopathology Flashcards
What are the two types of adaptive immune response?
Humoral and cellular
Name 6 pattern recognition receptors (PRRs)
Toll-like receptors (TLRs), NOD-like receptors (NLRs), rigl-like receptors (RLRs), C-type lectins (CLRs), scavenger receptors
Name the 5 major components of the innate immune system
pattern recognition receptors (PRRs), antimicrobial peptides, cells, complement components, cytokines
What is meant by pattern recognition receptors?
inclusive term for antigen recognition receptors in innate immune system (initial alert to any sort of infection)
What are the two groups of pattern recognition receptors?
1) cell-surface and intracellular receptors (TLRs, NLRs, RLRs, CLRs)
2) fluid-phase soluble molecules
How do fluid-phase recognition molecules bind?
Via Carbohydrate-recognition domains (CRDs)
What is the role of antimicrobial peptides?
These are in places like the saliva and they aim to destroy a pathogen before the immune system is even aware of it
What are cytokines?
Chemical messengers of the innate immune system
What are collectins?
A type of fluid-phase recognition molecule
What are the main roles of colletcins?
role in neutralisation of pathogen and recruitment of adaptive response
What are the major roles of marcophages in innate immunity?
phagocytose and kill bacteria, produce antimicrobial peptides, produce inflammatory cytokines
What are the major roles of plasmacytoid dendritic cells in innate immunity?
produce large amounts of interferon
What are the major roles of myeloid dendritic cells in innate immunity?
produce interleukin 12 and 10
Where are denderitic cells found?
T cell zones of lymphoid organs (circulate in blood)
What are the major roles of natural killer cells in innate immunity?
kill foreign and host cells with low levels of MHC+ self peptides
What are the major roles of neutrophils in innate immunity?
phagocytose and kill bacteria, produce antimicrobial peptides
What are the major roles of eosinophils in innate immunity?
kill invading parasites
What are the major roles of mast cells and basophils in innate immunity?
release TNF, IL-6, IFN in response to a variety f bacterial PAMPs
What are the major roles of epithelial cells in innate immunity?
produce antimicrobial peptides, produce mediators of local immunity
Which mutate faster: the variable regions of pathogens or humans?
pathogens
What is unique on each lymphocyte of the adaptive immune system?
antigen receptor
What type of expansion do lymphocytes undergo in response to infection?
Clonal
What are the primary lymphoid organs and what are their functions?
Bone marrow and thymus.
Site of lymphocyte development and selection
What are the secondary lymphoid organs and what are their functions?
Spleen, lymph nodes, mucosal surfaces.
Immune response.
How is the specificity of T and B cell antibody receptors achieved?
Each is made up of fragments to enable a magnitude of different variations
Briefly describe the mechanism of antigen presentation
antigens internalised and broken down to peptides; peptides associate with newly synthesised calss 2 molecules and brought to cell surface; if foreign, they are recognised by Th cells which are then activated
What are major histocompatability antigens?
Glycoproteins found on the surface of cells which make us unique
How many classes of histocompatability antigen are there?
2
What does HLA stand for?
Human leucocyte antigen
Name the 3 class 1 histocompatability antigens
HLA-A, HLA-B, HLA-C
Name the 3 class 2 histocompatability antigens
HLA-DP, HLA,DQ, HLA-DR
What cells do MHC class 1 proteins present peptides to?
cytotoxic T cells
What cells do MHC class 2 proteins present peptides to?
helper T cells
What must antigens be associated with in order for T cells to ‘see’ them?
MHC proteins
What is the function of B lymphocytes?
develop potential to secrete antibodies (humoral immunity)
What is the function of cytotoxic T lymphocytes?
kill pathogens (cellular immunity)
What is the function of helper T lymphocytes?
secrete growth factors (cytokines) to control immune response
What is the function of suppressor T lymphocytes?
damp down the immune response
Define immunosuppression
a natural or artifical process which turns off the immune response, partially or fully, accidentally of on purpose
Define immunodeficiency
the lack of an efficient immune system - susceptibility to infections
Define hypersensitivity
undesirable, damaging, discomfort-producing and sometimes fatal reactions produced by the normal immune system in a pre-sensitised host
Name the 4 types of hypersensitivity
I - IgE mediated
II - cytotoxic
III - immune complex
IV - cell mediated
Which type of hypersensitivity is anaphylactic?
Type I (IgE mediated reaction)
What are the clinical features of type I hypersensitivity?
fast onset (15-30 mins), weal and flare, can have 2nd phase response
What is the immunopathogenesis of type I hypersensitivity?
IgE Ab mediated mast cell and basophil degrannulation - release of performed and de novo synthesised inflammatory mediators
What do mast cells induce in early phase response of type I hypersensitivity?
degranulation and synthesis of lipid mediators
What is the role of kallikrein in type I hypersensitivity?
activates bradykinin
What is the role of histamine in type I hypersensitivity?
stimulation of irritant nerve receptors, smooth muscle contraction, increase in vascular permeability
What are lipid mediators derivatives of?
arachidonic acids
What is the role of eosinipohils in late phase response of type I hypersensitivity?
Granules containing cytotoxic proteins are attracted to site where contents released causing major tissue damage
Cytokine-driven activity is the major source of what in allergic responses?
pathogenesis
In type II hypersensitivity, what does binding of antibody to antigen result in?
Activation of complement cascade adn aggregation of Fc portions of immunoglobulins
Which type of immunoglobulin inniates type II hypersensitivity?
IgM or complement-binding IgG (IgM»IgG1&IgG3)
What type of cells are usually affected by type Ii hypersensitivity?
haematopoietic
Name 2 examples of type II hypersensitivity reactions?
blood group incompatability, autoimmune haemolytic anaemia
What is the 6 stage process of type III hypersensitivity?
1) IgG + Ag = AgAb complex
2) FcR in complex bind C1q
3) complement activation leads to generation of activated complement fragments
4) C5a attracts neutrophils and C3b initiates opsonisation
5) attempted phagocytosis of complexes
6) tissue damage
How is type IV hypersensitivity mediated?
T cell mediated - CD4+ helper T cells recognize antigen in a complex with Class II major histocompatibility complex
What type of reaction is contact dermitis?
combination of DTH and cytotoxic reaction
What is a granuloma?
A focal collection of inflammatory cells in tissues
What must be released to initiate a granulomatous reaction?
IL-12 (released by macrophages)
Name 3 infectious granulomatous diseases
tuberculosis, atypical mycobacteria, leprosy
