Innate Immunity Flashcards
Name some features of innate immunity?
-“inbuilt”, present from birth -not enhanced by second exposure (has no memory) -Uses cellular and soluble components Rapid response,minutes to hours, cooperates with and directs adaptive immunity
Recall the physical barriers used by the immune system in host defence?
Anatomical(physical) Skin-mechanical barrier, acidic environment Mucous membranes- mucus secretions trap microorganisms, cilia expel microorganisms
Recall the chemical (physiological) barriers used by the immune system in host defence?
-Body temperature/fever -Low pH- acidic pH of stomach kills many ingested microorganisms -Chemical mediators-lysozyme, interferons,complement
What does inflammation do?
local vascular permeability increases
Name the different tyoes of innate immunity defensive barriers?
Anatomical(physical) Physiological Phagocytic Inflammatory
Name the different cell types of the immune system?
Nuetrophil Eosinophil Dendritic cell Mononcyte/macrophage Basophil Mast cell Natural killer cell Never Ever Did My Baby Meet Norman
Name the function and mechanism of Neutrophils?
Phagocytosis and killing microbes
Name the function and mechanism of Eosinophil?
Phagocytosis,granule release, defence against parasitic infections and help B cell responses in GALT (IgA production) and involved in allergies
Name the function and mechanism of Basophils?
Granule release, may act as APC for “type 2 immunity” also involved in allergies and the release of histamine (hay fever)
Name the function and mechanism of monocyte/macrophages?
Phogocytosis,killing, cytokine release act as APC (antigen presenting cell)
Name the function and mechanism of Mast Cells?
Granule release (pro- inflammatory)
Name the function and mechanism Dendritic cell?
Antigen capture and presentation
Name the function and mechanism of Natural killer cells?
Lysis of infected cells
Name major features of nuetrophils?
(polymorphonuclear leukocyte) 40-75% of leukocytes; short lived cells, circulate in blood then migrate into tissues; first cells to be recruited to a site of tissue damage/infection
Name the major features of macrophages?
less abundant, dispersed throughout the tissues; signal infection by release of soluble mediators
To fight infection neutrophils need to….
- move from circulation into tissues to site of infection 2. bind pathogen 3. phagocytose pathogen 4. kill pathogen
What is opsonisation?
opson = greek for a sauce or relish coating of micro-organisms with proteins to facilitate phagocytosis opsonins are molecules that bind to antigen, and also can be bound by phagocytes antibody and complement function as opsonins
Name some oxygen-independent killing mechanisms for nuetrophils?
enzymes lysozyme hydrolytic enzymes antimicrobial peptides (defensins)
Name some oxygen-dependent killing mechanisms for nuetrophils?
respiratory burst: superoxide anion hydrogen peroxide singlet oxygen hydroxyl radical reactive nitrogen intermediates nitric oxide
How can nuetrophils form Neutrophil Extracellular Traps?
Activated neutrophils release granule proteins and chromatin to form extracellular fibres
What do mast cells release?
Secrete histamine and other inflammatory mediators, including cytokines
What can activate Mast cells?
What do Mast cells Lead to?
Leads to vasodilation and increased vascular permeability
Can Mast cells recognise, Phagocytose and kill Bacteria?
Yes
What are Natural Killers cells important for?
Important in defence against tumour cells and viral infections (esp.herpes)
Are natural killer cells Large granular lymphocytes?
yes
What do the recptors of natural killer cells bind to?
The receptors bind to antibody-coated cells (Antibody Dependent Cell-mediated Cytotoxicity)
Natural killer cells have antigen-specific receptors and express both activating and inhibatory receptors: balance of signals?
First part false and second part true.
What are cytokines?
-Small secreted proteins -Cell-to-cell communication -“messengers” of the immune system -Generally act locally -Biological effects at very low concentrations -short-lived So Many So Called Money Bombs
Name the different types of cytokines?
interleukins (IL-x): between leukocytes interferons (IFN): anti-viral effects chemokines chemotaxis, movement growth factors cytotoxic tumor necrosis factor (TNF)
What do chemokines do?
They are required for chemotaxis and recruitment of cells to particular sites
What are growth factors required for?
growth factors are required for the development of cells in the immune system
What type of effects do interferons have?
Have anti-viral effects
What do cytotoxic cytokines do?
They can induce cell death: tumour necrosis factor
Where are dendritic cells located?
near the skin and mucosal epithelia
Dendritic cells do not secrete pathogens?true or false
false dendritic cells secrete cytokines
How do dendritic cells work in the immune system and where do they migrate to ?
-Recognise and engulf pathogens -Migrate to lymph nodes to present antigens to the adaptive immune systems
What does the complement system lead to?
What is the complement system?
A complex series of proteins in serum and in tissues which form a triggered enzyme cascade system, leading to opsonisation of micro-organisms, direct killing of microorganisms, promotion of inflammation and recruitment of luekocytes
What major role does the complement system play?
Plays a major role in complementing the activity of specific antibody.
What does the complement system cause that leads to the opsonisation of microorganisms?
Triggered enzyme cascade system
Name some features of the complement system?
Plays a major role in complementing the activity of specific antibody complex series of ~30 proteins and glycoproteins, total serum conc. 3-4 mg/ml triggered enzyme cascade system rapid, highly amplified response components produced mainly in the liver, but also by monocytes and macrophages
Name the three pathways of complement activation?
The Classical Pathway The Alternative Pathwway The Lectin Pathway
Describe the triggered enzyme cascade system?
-Components are present in the body as inactive enzyme precursors -initial event is rapidly amplified -To become activated a protein has to have a part of it cleaved- this makes it an activated enzyme -This enzyme then cleaves of a part of another protein making it an activated enzyme. (because it is an enzyme it can cleave multiple protiens) -They go on and cleave of another part of another protein
Name the pathways that activate that triggered enzyme cascade?
The Classical Pathway initiated by antigen-antibody complexes
The Alternative Pathway direct activation by pathogen surfaces
The Lectin Pathway antibody-independent activation of Classical Pathway by lectins which bind to carbohydrates only found on pathogens
What is the classical pathway?
The antibody binds to the antigen causing the enzyme cascade system
When is the alternative pathway activated?
Direct activation by pathogen surfaces involves complementary binding to the microbial surfaces doesn’t require antibodies
What is the Lectin Pathway?
antibody-independent activation of Classical Pathway by lectins which bind to carbohydrates only found on pathogens
What are lectins?
protein that can bind to carbohydrates only found in pathogens
Draw the complement activation pathway/
On the ppt slide
Name the functions of the Complement?
Lysis Opsonization Activation of inflammatory response Clearence of immune complexes
Local inflammatory response may be accompanied by a systemic response “acute phase” after how many days?
1-2 Days
What induces a systemic “acute-phase” response?
Cytokines
What symptoms are present in an acute-phase response?
Fever
Where are acute-phase proteins produced?
Liver
What protein is measured clinically as a marker of inflammation?
C-reactive Protein CRP
Name the four acute phase proteins?
C-Reacctive protein -Activates Complement Mannan binding Lectin(MBL)-activates complement complement fibrinogen(clotting)
What is the end result of a complement cascade ?
lysis opsonization Activation of inflammatory response clerance of immune complexes
Draw a diagram showing the complement activation pathways ?
add pic
What does the MAC form and how does it kill pathogens?
The membrane-attack complex (MAC) forms transmembrane channels. These channels disrupt the cell membrane of target cells, leading to cell lysis and death.
what is the complement system?
complement system is a part of the immune system that enhances (complements) the ability of antibodies and phagocytic cells to clear microbes and damaged cells from an organism, promotes inflammation, and attacks the pathogen’s plasma membrane. It is part of the innate immune system
Explain the principle of activating and inhibatory cell surface receptors for NK cells
Why are NK cells a part of the innate immune response?
Typically, immune cells detect major histocompatibility complex (MHC) presented on infected cell surfaces, triggering cytokine release, causing lysis or apoptosis. NK cells are unique, however, as they have the ability to recognize stressed cells in the absence of antibodies and MHC, allowing for a much faster immune reaction. They were named “natural killers” because of the initial notion that they do not require activation to kill cells that are missing “self” markers of MHC class 1.[1]This role is especially important because harmful cells that are missing MHC I markers cannot be detected and destroyed by other immune cells, such as T lymphocyte cells.
They lack an antigen specific receptor
What is an acute phase response?
It is a systemic inflammatory response caused by injury or infection.
In response to the injury local inflammatory cells (nuetrophils and macrophages) release many cytokines ( interleukins IL1, IL6 and IL8, and TNFα.).
These cytokines cause a fever and causes the liver to produce many acute phase proteins ( C-reactive protein, mannose-binding protein, complement factors, Serum A)
These acute phase proteins help fight infection by optimization and trapping of microorganism and their products, in activating the complement system, in binding .
Define MHC haplotype?
Haplotype is a group of MHC molecules linked to one chromosomes.
Different MHC haplotypes lead to differnt immune responses.
This definition of haplotype applies whether it is just a few genes or all of the genes on an entire chromosome11. In the case of the major histocompatibility complex, it is a group of more than 200 genes on chromosome 6 (Janeway et al. 2001). The set of alleles11 inherited together from one parent form the MHC haplotype. Thus, one offspring will inherit two different MHC haplotypes, one from each parent. The different haplotypes with so many genes helps keep genetic variation in the overall complex, which improves the immune response ability of the organism.
