Immunopathology Flashcards by Akash Dharni

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)

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What are the following examples of?

Defensins
Cathelin
Protegrin
Granulysin
Histatin

Antimicrobial Peptides

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Name 4 cell types in the innate immune system?

Macrophages
Dendritic Cells
NK Cells
T Cells
White cell line

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Which compliment pathways contribute to the innate immune system?

Classic and Alternative complement pathways

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What are the 2 groups of pattern recognition receptors?

Cell surface and Fluid Phase Soluble

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What are the fluid phase recognition molecules?

A group of microbial complex carbohydrates that bind via carbohydrate recognition domains

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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

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What are some roles of the fluid phase recognition molecules?

Neutralising pathogens

Recruitment of adaptive response

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What activates the classical pathway?

Antigen:Antibody complex at pathogen surface

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What activates the MB-Lectin pathway?

Mannose-binding lectin binding mannose on pathogen surface

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What activates the alternative pathway?

Pathogen surfaces

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At which point do all pathways converge?

C3 convertase

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What are the effects of IL1?

Increased coagulation
Increased inflammation
Increased fever
Increased acute phase proteins

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What are the sources of IL1?

Macrophages

Epithelium

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What are the sources of TNF?

Macrophages

T-Lymphocytes

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What are the effects of TNF?

Increased coagulation
Increased inflammation
Increased fever
Increased acute phase proteins

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What are the effects of IL6?

Increased acute phase proteins

Increase in proliferation of B cells

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What are the sources of IL6?

Macrophages
T Lymphocytes
Endothelium

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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?

1. ) Antigens are internalised 2. ) Broken down to peptides 3. ) Peptides associate with newly synthesised class 2 molecules and are brought to the cell surface 4. ) If peptides are foreign, they are recognised by helper T cells which are then activated 5. ) 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?

1. ) IgE mediated 2. ) Cytotoxic reaction 3. ) Immune complex reaction 4. ) 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