Innate Immunity - week 2 Flashcards
What are the main functions of the immune system?
Protects against infectious agents.
Detects and kills cancer cells.
Has the ability to distinguish, neutralise and destroy the non-self toxins or foreign bodies.
What are the issues that defence against foreign proteins can cause?
It may fight against the workings of gene therapies and transplants.
Outline the 4 main steps after infection
- Pathogens where to the epithelium
- Local infection, penetration of epithelium
- Local infection of tissues
- Adaptive immunity
What barriers are present against a pathogen adhering to the epithelium of a blood vessel ?
Normal skin flora, local chemical factors such as the natural pH of the skin and the oils being produced etc.
Phagocytes - especially in the lungs.
What happens to to prevent penetration of pathogens into the blood vessels?
Wound healing.
Induced antimicrobial proteins and peptides.
Complement system.
Phagocytes.
Macrophages and dendritic cells also often engulf and remove pathogens.
What is present to prevent local infections of the tissues?
Complement system.
Cytokines.
Chemokine.
Activation of macrophages.
Dendritic cells migrate to lymph nodes to initiate adaptive immunity.
Blood clotting to prevent spread of infection.
How do dendritic cells initiate adaptive immunity?
They migrate to the lymph nodes.
What is present as part of the adaptive immune system?
Infection cleared by specific antibodies.
T-cell dependent macrophages are activated.
Cytotoxic T-cells produced.
How quickly can the non-specific immune system destroy pathogens?
Very quickly
How effectively can the non-specific immune system destroy pathogens and why ?
Not very effective because it just destroys everything. Not specific.
Name some of the physical and chemical barriers that are part of the non-specific immunity
- Keratinisation in the skin.
- Mucus formation on the mucosal epithelium and cilia clearance in the respiratory tract.
- Production of various antimicrobial factors such as lysozyme, lactic and fatty acids.
- Microbial antagonism. by mutualistic and commensal microorganisms.
- Cytotoxicity by complement
- Phagocytosis and Netosis
What are mutualistic pathogens?
Microorganisms that benefit the host and the host benefits them.
What are commensal bacteria?
Organisms that use food supplied by the host.
How does cytotoxicity by complement act as a chemical barrier in the non-specific immune system ?
Kills any cells that may have got past other features of the innate immune system or any harmful cells which may have entered the blood stream.
What protein can be used as a good measure of inflammation?
C-reactive protein
What is usually the first antibody produced in a non-specific immune response?
IgM
Are memory cells part of the innate immune system?
No
What is the response to an infectious agent if there is a normal level of antigen present?
Protective immunity
What is the response to an infectious agent if there is a deficient level of antigen present?
Recurrent infection
What is the response to an innocuous substance if there is a normal level of antigen present?
Allergy
What is the response to an innocuous substance if there is a normal level of antigen present?
No response
What is the response to a grafted organ if there is a normal level of antigen present?
Rejection
What is the response to a grafted organ if there is a deficient level of antigen present?
Acceptance
What is the response to a self organ if there is a normal level of antigen present?
Autoimmunity
What is the response to a self organ if there is a deficient level of antigen present?
Self tolerance
What is the response to a tumour if there is a normal level of antigen present?
Tumour immunity
What is the response to a tumour if there is a deficient level of antigen present?
Cancer
When are immune responses likely to be harmful?
When you don’t have a great enough response - deficient immune response.
What are the mechanical defences that are part of the immune system on the skin?
Longitudinal flow of air or fluid.
What are the chemical defences that are part of the immune system on the skin?
Fatty acids
Beta defensins
Lamellar bodies
Cathelicidin
What are the mechanical defences that are part of the immune system in the gut?
Longitudinal flow of air or fluid.
What are the chemical defences that are part of the immune system in the gut?
Low pH
Enzymes
alpha defensives
Cathelicidin
What are the mechanical defences that are part of the immune system in the lungs?
Movement of mucus by cilia
What are the chemical defences that are part of the immune system in the lungs?
Pulmonary surfactant
alpha defensins
Cathelicidin
What is the main function of catherlicidin?
Wound healing
What are the mechanical defences that are part of the immune system in Eyes, nose and oral cavity?
Tears (lysozyme)
Nasal cilia
What are the chemical defences that are part of the immune system in Eyes, nose and oral cavity?
Enzymes in tears and saliva
Histatins
Beta defensins
Define antigen
A substance triggering the immune effector responses ad memory to this antigen.
What are the 2 categories of antigen?
Complete
Incomplete
What are incomplete antigens?
They cannot promos antibody formation by themselves but can do so when conjugated to a protein.
What are haptens?
Small compounds that penetrate the skin and generate modified self proteins as immunogenic antigens.
What are incomplete antigen often called?
Haptens
What are the antigen characteristics?
Antigenicity
Specificity
Immunogenicity
What does the innate immune system respond to ?
Molecular patterns on the cellular surface.
Is the innate immune system specific?
No
How fast is the innate immune system?
Immediate
What does the innate immune system use to recognise molecular patterns on the cellular surface?
Pattern Recognition Receptors
What are Pattern Recognition Receptors trainer to recognise as part of the innate immune system?
Pathogen associated molecular patterns
Where are pattern recognition receptors found ?
On the cell surface or intracellular soluble molecules
Define molecular patterns
Low-molecular weight substances evoking the reaction of the innate immune system.
What are the different types of molecular patterns?
Pathogen-associated
Allergen-associated
Damage associatd
Tumour associated
Name the different types of patter recognition receptors found on the cellular surface
Scavenger receptors
Lectin receptors
Toll-like receptors
How do scavenger pattern recognition receptors work?
They recognise cell debris that neutrophils and macrophages have left over.
What do lectin pattern recognition receptors recognise?
Bacterial carbohydrates
What do toll-like pattern recognition receptors recognise?
Pathogen associated molecular patterns
What are the triggers for both innate and adaptive immunity?
Innate - patterns
Adaptive - antigens
How quickly do both the innate and adaptive immune systems developed?
Innate - Rapid
Adaptive - slow
What is the fate of the pathogen in terms of innate and adaptive immunity?
Innate - immune containment.
Adaptive - Immune clearance.
What are the different memories for both innate and adaptive immunity?
Innate - No formation of monoclonal memory after a primary infection.
Adaptive - Formation of long-term monoclonal memory after a primary infection.
What are the crucial cells in both innate and adaptive immunity?
Innate - Phagocytes, NK cells, mast cells
Adaptive - T cells and B cells
What are the effector events in both innate and adaptive immunity ?
Innate - ‘Acute phase recognition’, complement activation, phagocytosis, NETosis, pyropoptosis, simple inflammation, apoptosis.
Adaptive - Antigen neutralisation by antibodies, immune inflammation, induced apoptosis in target cells.
What are the selection theories in both innate and adaptive immunity?
Innate = pattern recognition theory.
Adaptive = clonal selection theory.
How does immunopathology work in both the innate and adaptive immune response?
Innate - Immunodeficiency and auto inflammatory disorders.
Adaptive - Immmuodeficiecy, autoimmune diseases, allergic disorders.
What are pattern recognition receptors?
Molecules expressed by cells of the innate system, which capable of sensing “patterns” triggering the reactions of the innate immune system.
What are the 5 types of pattern recognition receptors?
- Toll-like receptors
- C-type lectin receptors
- NOD-like receptor
- RIG-1 like receptors
- AIM-2 like receptors
Where are toll-like receptors found?
The membranes of macrophages, neutrophils, dendritic cells, lymphocytes, epithelial cells, platelets, splenocytes, atheoscletotic plaques and some endosomal cells.
How do TLRs become activated?
Ligands bind to them
Once ligands have bound to TLRs what do they do?
They transduce signals that eventually lead to the activation of inflammasome and proptosis.
What is pyroptosis?
Highly inflammatory form of programmed cell death.
What type of molecular patterns do toll-like receptors recognise?
Pathogen associated and damage associated molecular patterns.
Where are C-type lectin receptors found?
Bound to the cell membranes
What are C-type lectin receptors mainly involved in?
Fungal recognition and endocytosis
Why are C-type lectin receptors compatible to toll-like receptors?
They recognise both patterns and antigens and can therefore bridge the innate and adaptive immunity.
Why can toll-like receptors link the innate and adaptive immunity?
Because they recognise antigens.
What are the main roles of C-type lectin receptors?
They are anti fungal, antitumoural and antimycobacterial.
Where are NOD-like receptors found?
Cytosol
What does NOD mean in terms of nod-like receptors?
Nucleotide-binding oligomerisation domain
What do NOD1 receptors recognise?
Peptidoglycan of gram -ve bacteria
What do NOD2 receptors recognise?
Intracellular muramyl dipeptide on both gram -ve and gram +ve