Immunopathology Flashcards
What are pattern recognition receptors?
proteins expressed by cells of the innate immune system to identify two classes of molecules: pathogen-associated molecular patterns (PAMPs), which are associated with microbial pathogens, and damage-associated molecular patterns (DAMPs)
What are the following examples of?
Defensins Cathelin Protegrin Granulysin Histatin
Antimicrobial Peptides
Name 4 cell types in the innate immune system?
Macrophages Dendritic Cells NK Cells T Cells White cell line
Which compliment pathways contribute to the innate immune system?
Classic and Alternative complement pathways
What are the 2 groups of pattern recognition receptors?
Cell surface and Fluid Phase Soluble
What are the fluid phase recognition molecules?
A group of microbial complex carbohydrates that bind via carbohydrate recognition domains
What family of molecules are examples of fluid phase recognition molecules?
Collectins, belonging to the C-Type Lectin Family
Collectins: Mannan Binding Lectin
Surfactant protein A+D
What are some roles of the fluid phase recognition molecules?
Neutralising pathogens
Recruitment of adaptive response
What activates the classical pathway?
Antigen:Antibody complex at pathogen surface
What activates the MB-Lectin pathway?
Mannose-binding lectin binding mannose on pathogen surface
What activates the alternative pathway?
Pathogen surfaces
At which point do all pathways converge?
C3 convertase
What are the effects of IL1?
Increased coagulation
Increased inflammation
Increased fever
Increased acute phase proteins
What are the sources of IL1?
Macrophages
Epithelium
What are the sources of TNF?
Macrophages
T-Lymphocytes
What are the effects of TNF?
Increased coagulation
Increased inflammation
Increased fever
Increased acute phase proteins
What are the effects of IL6?
Increased acute phase proteins
Increase in proliferation of B cells
What are the sources of IL6?
Macrophages
T Lymphocytes
Endothelium
What are the sources of IL23?
Macrophages
Dendrites
What are the effects of IL23?
Increase in IL17
What are the major roles of a macrophage in innate immunity?
Phagocytose and kill bacteria
Produce AMPs
Bind LPS
Produce inflammatory cytokines
What are the major roles of dendritic cells in innate immunity?
Produce large amounts of IFN which has antitumor and antiviral activity
Found in T cell zones of lymphoid organs
Circulate in blood
What are the major roles of NK cells in innate immunity?
Kill foreign and host cells that have low levels of MHC + self peptides
Express NK receptors that inhibit NK function in the presence of high expression of MHC
What are the major roles of Neutrophils in innate immunity?
Phagocytose and kill bacteria
Produce ANPs
What is the major role of eosinophils in innate immunity?
Kill invading parasites
What are the major roles of mast cells and basophils in innate immunity?
Release TNF, IL6, IFN in response to bacterial PAMPs
What is the role of epithelial cells in innate immunity?
Produce AMPs
Tissue specific epithelia produce mediator of local innate immunity
What is the adaptive immune response?
An evolution in response to changing pathogen structures
How does the adaptive immune response generate diversity?
Utilises existing systems to generate diversity of antigen receptors
What is the mechanism of antigen presentation?
- ) Antigens are internalised
- ) Broken down to peptides
- ) Peptides associate with newly synthesised class 2 molecules and are brought to the cell surface
- ) If peptides are foreign, they are recognised by helper T cells which are then activated
- ) Helper T cells produce cytokines
Which cell type do MHC1 proteins present peptides to?
Cytotoxic T cells
Which cell type do MHC2 proteins present peptides to?
Helper T cells
How does binding of antibodies to antigens inactivate them?
Neutralisation: blocks viral binding sites or coats bacteria
Agglutination of microbes
Precipitation of dissolved antigens
Activation of complement system (leads to lysis)
What is immunosuppression?
A natural or artificial process which turns off the immune response partially, or fully, accidentally or on purpose
What is immunodeficiency?
The lack of an efficient immune system, increasing susceptibility to infections
What is hypersensitivity?
Undesirable, damaging, discomfort-producing and sometimes fatal reactions produced by the normal immune system, in a pre sensitised host
What are the 4 types of hypersensitivity?
- ) IgE mediated
- ) Cytotoxic reaction
- ) Immune complex reaction
- ) Cell mediated reaction
What is the immunopathology of Type 1 hypersensitivity reaction?
IgE Ab mediated mast cell and basophil degranulation releases preformed (histamine) and newly synthesised (leukotrienes) inflammatory mediators
What are the clinical features of anaphylactic reactions?
Fast onset
Weal and flare
Can have a late 2nd phase response
What are the common antigens for type 1 reactions?
Pollen, Bee venom, animal dander
What are some characteristics of IgE?
Produced by plasma cells from class switched B cells under the control of IL4 and CD40L-CD40 interaction
Extremely low serum levels
High affinity receptor
Permits stable binding over long periods
Describe the early phase response of type 1 reactions at the mast cell
FCR1 present at high density
Cross linking of FCR1 by allergen leads to activation of was cell resulting in degranulation and synthesis of lipid mediators
What does histamine do in the body?
Stimulation of irritant nerve receptors
Smooth muscle contraction
Increase in vascular permeability
What does kallikrein do?
Activates bradykinin
What are some characteristics of eosinophils in the late phase response?
Granules contain cytotoxic proteins
Attracted to site of allergic inflammation by chemokines
In tissues they release contents of granules
What is the major source of pathogenesis in allergic responses?
Cytokine driven activity
