Innate Immunity Flashcards
What is innate immunity?
The defence system that one is born with
What does innate immunity depend on?
Physical and chemical barriers
What is the function the physical and chemical barriers?
First line of defense in the immune response
What is a self-marker?
They are recognised by the immune system of an organism as being part of that organism.
What causes the self marker to be recognised?
The presence of marker molecules known as HMC
What is non-self?
Agents that are not recognised by the immune system as being part of the organism.
What identifies non-self?
The presence of receptors that identify the agent as an antigen.
What does innate immunity look for?
PAMPs and DAMPs
What are PAMPs?
Pathogen associated molecular patterns
What are DAMPs?
Danger associated molecular patterns
Where are PAMPs derived from?
Microorganisms and thus drive inflammation is response to infections.
What is a well known PAMP?
Lipopolysaccharide, cell wall of gram-negative bacteria
Where are DAMPs derived from?
Host cells, such as tumour cells, dead or dying cells, products released from cells in response to signals
What do DAMPs induce?
Sterile inflammatory response
Where are DAMPs created or exposed to?
Environments of trauma, schema or tissue damage
Which molecular patterns do not require a pathogenic infection?
DAMPs
Examples of environments where DAMPs appear?
MI, cancer, autoimmune disease, atherosclerosis
How are PAMPs and DAMPs recognised?
Immune cells have pattern recognition receptors
What follows after the binding of the PRRs to PAMPs/DAMPs?
Recruitment of phagocytes, natural killer cells and leukocytes
What are the three lines of defence?
Physical and chemical barrier,
Innate Immune Response
Adaptive Immune Response
What are some examples of physical first lines of defence?
Skin,
Nasal hair,
Eyelashes & Eyelids
Mucous Membranes
Mucociliary Clearance
Urination
What are some examples of chemical first lines of defence?
Low pH (skin, gastric acid, vagina)
Antimicrobial molecules (IgA, Sebum, Mucous)
What are some examples of biological first lines of defence?
Microbiome
What is the process of innate immunity?
Phagocytes bind to pathogen
Wrap around their cell membrane around pathogen
Engulf pathogen and destroy them
Pathogens are broken into small pieces and displayed to phagocytes
Recognised cytosine T-cells, destroy the phagocytes with pathogen inside
During phagocytosis what do the receptors bind?
Bind ligand molecules on the target such as pathogens or dead cells.
What happens as receptors bind more and more ligand molecules?
Cell membrane progressively engulfs the target
What happens upon full engulfment?
Phagosome is formed, fuses with lysosomes leading to digestion of target.
What is the process of the complement system?
Complete protein activated –> Recruit WBC to the site of infection which triggers inflammatory response.
Which are the non-specific defence mechanisms?
First and second lines of defence
What is the specific defence mechanism?
Third line of defence
When is third line of defence activated?
When other first and second lines of defence have been exhausted
What are the main phagocytes?
Macrophages
What are the macrophages in the lungs called?
Alveolar macrophage
What are the macrophages in the liver called?
Kupffer cells
What are the macrophages in the connective tissue called?
Histocytes
Why do macrophages release cytokines?
To bring in reinforcement: neutrophils
What are neutrophils?
Granulocytes that contain histamine
What does histamine cause?
Vasodilation and thus triggers inflammation
Where are mast cells found?
Reside in connective tissue and mucous membranes
What are mast cells?
They play an important role when it comes to healing process and protection against pathogens
What is the function of NK cells?
Thye do NOT attack the pathogen directly but instead they detect when cells are infected by pathogen and trigger a progress called apoptosis
What do NK cells release?
Substances like perforins and granzymes
What are perforins?
Perforate cell wall making holes through-out the membrane
What do granzymes do?
Enter the cells and trigger apoptosis
What are dendritic cells?
Develop from monocytes and are also called antigens
Where are dendritic cells found?
In direct contact with the external environment areas
What is the function of the dendritic cells?
ID pathogens and present them ti the rest of the immune system triggering a non-specific inflammatory response
What is the function of cytokines?
Essential for the communication of signals in both innate and adaptive immunity
What are cytokines?
Small soluble proteins that confer instructions and mediate communication along immune and non-immune cells
What do cytokines do?
They initiate and constrain inflammatory response to pathogens and injury
What is the role of the inflammatory cytokines?
Initiate and regulate the host defense against pathogens mediating the innate immune response
What is the complement system?
Set of proteins made in the liver and released into the blood. They float around waiting for something to trigger them so that they become activated.
What is the complement system divided into?
Classical pathway and alternative pathway
What is the % of basophils and mast cells?
0.5 to 1% (rare)
Which cells’ function is fighting parasitic infection, allergic reactions blood clotting because they contain heparin?
Basophils
What is the mast cells’ function?
Wound healing, inflammation, and serious allergic reactions
What are the most common white blood cells?
Neutrophils
What is neutrophils’ function?
Phagocyte and destroy invaders.
Which are the first cells to respond to an infection?
Neutrophils
What is the % of eosinophils?
1 to 3%
What is the primary function of eosinophils?
Destroy invaders, Ab-coated parasites
What is the % monocytes and macrophages?
1 to 6%
What is the function of monocytes and macrophages?
Phagocyte and destroy invaders
What do macrophages do?
They have antigens on the surface to trigger to engulf and destroy bacteria. They also stimulate cytokines.
What is the % of lymphocytes?
20 to 35%
What is primary function of lymphocytes?
Antibody production
Which cells’ functions are to recognize pathogens and activate other immune cells?
Dendritic cells
Which is the most common pathway of the complementary system?
The alternative pathway
What is the lectin pathway?
Activation through mannose binding lectins
What are the common themes between the three pathways?
Lead to the formation of C3 convertase, the cleavage of C3 and the formation of C5 convertase
What is the function of the C5 covertase?
Initiates the activation of late components of the complement system to form membrane attack complex, which kills the pathogen.
What is the leukocyte migration?
A passage from the tissue to the blood and lymphatic vessels and from the vessels to the tissue.
What is the process of leukocyte migration?
Capture and rolling
Activation,
Arrest,
Transmigration
What is chemotaxis?
Movement of leukocytes toward sites inflammation
What attracts the leukocytes to the site of injury?
The chemicals that trigger an inflammatory response
How can leukocytes respond?
In a specific or nonspecific defence
What causes chronic inflammation?
Trauma and infection
Diet
Low sex hormones
Smoking and alcohol
Stress
Poor sleeping habits
What are the stimuli that give rise to inflammation?
DAMPs (physical and chemical)
PAMPs (immunological and infections)
What are DAMPs?
Molecules that alert the molecule about danger, stimulate an inflammatory response and promote regeneration.
What are PAMPs?
They serve as ligands for host pattern recognition molecules such as Toll-like receptors.
Why does a transudative occur?
Due to the increase hypostatic pressure or low plasma osmotic pressure
What is pleura effusion?
Accumulation of fluid within the pleural space
Why does an exudative occur?
Due to the inflammation and increased capillary permeability
What is the difference between transudate and exudative?
Transudate is the fluid build-up caused by systemic conditions that alter the pressure in blood vessels making fluid leave the vascular system.
Exudate is fluid buildup caused by tissue leakage due to inflammation or local cellular damage.
What is the role if neutrophils in immunity?
- Patrol the organism for signs of microbial infections, and when found, they respond to trap and kill the invading pathogens.
What is the onset for acute and chronic inflammation?
acute: immediate
chronic: Delayed
Which kind of inflammation lasts only a few days?
Acute
How long does chronic inflammation last?
Upto months or years
What are the causative agents for acute inflammation?
Bacteria or injured tissue
Persistent acute, foreign body or viral autoimmune are all causative agents of which inflammation?
Chronic
What are the major cells for acute inflammation?
Neutrophils, basophils, monosystemacrophages
What are major cells in chronic inflammation?
Mononuclear cells, mono lymphocytes, plasma cells and fibroblasts
What is the outcome of acute inflammation?
Resolution of abscess formation, chronic inflammation
What are the primary mediators of acute inflammation?
Vasoactive amines
What are the primary mediators of chronic inflammation?
Eicosanoids
Tissue destruction, fibrosis, and necrosis are all the outcomes of which kind of inflammation?
Chronic inflammation
