Innate Immunity Flashcards by Joshua Parker

What are the 3 primitive prevention barriers?

Anatomical barriers (eg. Skin)
Chemical defences 
Commensal microflora

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What are the functions of the innate system?

Prevent access of pathogens
Recruit immune cells to infection site
Detect and remove pathogens
Activation of APCs

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How does the skin protect the body? (3)

Epidermis is a physical barrier
Secretion of antimicrobial peptides
Fatty acids in sebum

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How does the mucosal epithelium (eg. Gastrointestinal surface) protect the body? (2)

Antimicrobeles in saliva and mucus

Mucus secretion contains glycoproteins which prevent microbial adhesion

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What is the purpose of lysosomes in bacterial defense?

Makes the microbes membrane accessible to antimicrobial proteins

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What are 3 chemical defences?

Low pH
Bile
Pulmonary surfactant

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How do commensal microflora help prevent pathogens? (2)

Compete with pathogens for attachment sites and nutrients

Support host by aiding digestion, promote maturation of immune cells

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How many antimicrobial peptides are identified?

800

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What pathogens do antimicrobial peptides work against?

Bacteria, fungi and viruses

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What are antimicrobial peptides?

Positively charged peptides up to 60 amino acids

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What are cytokines? (3)

Low MW proteins secreted by immune cells
Bind to specific cell surface receptors
Can act on self (autocrine) nearby (paracrine) or circulated (endocrine)

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What are the four families of cytokines?

Hematopoietin
Interferon
Chemokine
Tumour necrosis factor

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What do the cytokines families hematopoietin and chemokine family do?

Hemato: interleukins (communication between leukocytes)
Chemo: adhesion,chemotaxis and leukocyte activation

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What do the cytokines families interferon and tumour necrosis factor do?

Tumour: inflammation
Interferon: anti viral

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How are pathogens recognised by innate immunity

Pathogen associated molecular patterns on the pathogen are detected by pattern recognition molecules and receptors

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What are the three types of pattern recognition molecules and receptors?

Soluble PR molecules
Cell membrane phagocytic receptors
Cell membrane and cytoplasmic signalling receptors

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What is the basic principle of phagocytic PRRs (pattern recognition receptors)?

Cell membrane receptors stimulate ingestion of known pathogens

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What are 3 mechanisms of phagocytosis?

Innate immune system components, eg. Neutrophils
Different types of PRR (pattern recognition receptors)
Effector mechanisms of phagocytosis

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What are the two types Effector mechanisms?

Non oxidative

Oxidative

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What is the method of non oxidative effector mechanism attack?

Granules with phagocytic potential merge with endosomes to form phagolysosomes

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What is the method of oxidative effector mechanism attack?

Employs reactive oxygen and nitrogen species (ROS, RNS)

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What is the mechanism of oxidative phagocytosis? (4)

Activation of G protein coupled receptors
Activates NADPH oxidase.
Causes respiratory burst.
Causes ROSs eg. Superoxide

Activates inducible nitric oxide synthase
Causes RNS (nitric oxide)

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How does a respiratory burst cause cell death if ROSs are continually made?

Causes build up within cell of ROSs and destroy it within

What are the 3 types of cytoplasmic signalling receptor?

Toll like receptors
C type lectin receptors
Nod like receptors

What does PRR activation change within the cells gene expression? (3)

Causes more expression of; antimicrobial peptides Type I interferons Cytokines

What is the basic principle of toll like receptors?

Each receptor set detects distinct molecular pattern not present in healthy vertebrates

What are the 5 main characteristics of neutrophils?

``` First cells to arrive at infection site Defend against bacteria and fungi Act mainly via phagocytosis Display several types of TLR (toll like) and PRR (pattern recognition) Contain primary and secondary granules ```

What are the main characteristics of monocytes?

Circulate in the blood before ~8 hours before migration into tissue

What are the 3 main characteristics of macrophages?

5-10x bigger than monocytes More intracellular organelles Can be residential or wandering

How do residential macrophages differ from wandering?

Different functions and have different names, eg. Kupffer cells in liver

What are the 4 main characteristics of dendritic cells?

Phagocytic APCs Display MHC class I and II molecules Take up pathogens by pinocytosis and receptor mediated endocytosis On maturation migration to lymph nodes

What are the 4 main characteristics of eosinophils?

Phagocytic granulocytes Mainly located in tissues Have effector function Release prostaglandins (increase inflammotory response)

What are the 2 main characteristics of basophils?

Nonphagocytic granulocytes | Move from blood into tissue when needed

What are the 3 main characteristics of mast cells?

Differentiate only upon entering tissues Secrete cytokines and histamine Play role in inflammation and allergic reactions

What are the 4 main characteristics of natural killer cells?

Only kill cells that are missing 'self' component Contains cytotoxic granules Express activating receptors (trigger killer cells) Express inhibiting receptors (normal levels of MHC I molecules)

How is NK cytotoxicity apoptosis induce apoptosis?

Fast dependant mechanism Fast independent mechanism Antibody dependant cell cytotoxicity (ADCC)

What does ADCC stand for?

Antibody-dependant cell cytotoxicity

What is the function of the complement?

Recognition and destruction of extracellular pathogens

How does the complement system destroy pathogens? (4)

Lysis of cells Opsonisation then phagocytosis Triggering inflammation Clearance of immune complexes

What is opsonisation?

The process in which a antibody is marked for phagocytosis

What are the four signs of acute inflammation?

Calor (Heath) Rubor (redness) Tumour (swelling) Dolor (pain)

What are the 3 roles of inflammation?

Recruit effector molecules to infection site Induce local blood clotting Initiate tissue repair

What 2 factors initiate inflammation?

Tissue damage | Pathogen recognition

What 4 blood systems activate when tissue damage inflammation occurs?

``` Kinin system (enzyme cascade) Clotting system (increased vascular permeability) Fibrinolytic system (compliment activation) Complement (anaphylatoxins) ```

What happens when pathogen activated inflammation occurs?

Prostaglandins and leukotrienses are released | Chemokines are released

What do chemokines do?

Alter cytoskeleton and adhesiveness of target cells

What are CAMs?

Cell adhesion molecules

What are the 4 different CAM types?

Selectins lg CAMs Mucins Integrins

What are the roles of selectins and lg CAMs?

Sele: bind sialylated carbohydrates lg: adhesion of phagocytes to endothelial

What are the roles of mucins and integrins (cams)?

Mucins: bind to selectins Integrins: bind extracellular molecules

What are the steps involved in leukocyte extravasation (cell adhesion)?

Rolling freely Activated by chemoatractant Arrest/adhesion, mediated by integrins Transendothelial migration (move into cell)

what are the of TNFalpha and TGFbeta (3)

TNFalpha: activate macrophages and neutrophils TGFbeta: limits inflammatory response and promotes tissue repair

What for events take place during systematic system response to inflammation?

Fever Synthesis of ACTH production of leukocytes Acute phase protein production

What causes chronic inflammation?

Pathogens resistant to immune defences Autoimmune diseases Cancer

What are the consequences of chronic inflammation? (3)

Continuous activation of macrophages Fibrosis (scarring of tissue) Granuloma (cause lesions)

What is sepsis?

Spread of an infection from original site to bloodstream

What are the consequences of sepsis?

Triggers blood clotting in small vessels which leads to multiple organ failure