Module 2 Flashcards
Innate immunity is known as ?
The first line of defence and will function non specifically
What are the barriers of the innate immune system ?
physical barriers, cellular barriers and solubale barriers
Physical barrier is made up of?
made up of both physical and chemical processes
Physical processes of the physical barrier ?
skin and the mucous membrane that contains cilia and mucous to trap pathogens
chemical components of physical barrier ?
Tears and saliva a because they have lyzoymes
Gastric acid , which will destroy pathogens
Cells that make up the cellular barrier in innate immunity
Neutrophils, macrophages, Natural killer cells , dendritic cells
Neutrophils
most common leukocyte and act as phagocytes that will patrol and kill pathogens , circulate for 12H in blood and are recruited to infection sites by resident marcophages
Macrophages
phagocytes that patrol for pathogens which they will engulf , will either take up residence in tissue or patrol larger tissue areas, present antigen to T cells, get activated after phagocytosing or from cytokine signalling
Dendritic cells
phagocytes that are in contact with the external environment , engulf foreign antigens that evaded the initial barriers and will present them on MHC complexes which are recognized by helper T cells
Link between adaptive and innate systems
natural killer cells
recognize abnormal cells that lack antigen- specific receptors, will bind to cell surface of target cells and release chemicals causing pores to form and lysis to take place
Destroy abnormal cells of the body including tumour cells and virus infected cells
what is the soluable barrier made out of ? what is the role ?
The complement system and cytokines which are important for developing a inflammatory innate immune response that takes place after penetration of infectious agent
explain the complement system
made of 30 proteins which will normally circulate in an inactive form
activated directly by pathogen or indirectly by pathogen bound antibody
complement system activation causes ?
cascade of reactions creating a membrane attack complex ( will create holes in cellular membranes ) while also enhancing the other immune functions like inflammation and phagocytosis
Pathways to activate complement system
classical, alternative and lectin
functions of the complement system
inflammation , phagocytosis and membrane attack complex
inflammation in the complement system
attraction of immune cells at the infection site through chemotactic molecule release like histamine and cytokines
Activated complement proteins will bind to receptors on immune cells to release histamine and cytokines
phagocytosis and the complement system
activated complement protein C3B will opsonize pathogens targeting them for phagocytosis
Membrane attack complex and complement system
attacks pathogens through the formation of holes which leads to lysis and cell death
What is a cytokine ?
proteins that play a key role in cell to cell communication and are secreted by immune cells in response to different stimuli
cytokine signalling is needed for
regulate immune processes such as hemopoteisis and inflammation
autocrine effects of cytokines
sending and recieving signal is the same
paracrine effects of cytokines
sending and recieving cells are near each other
endocrine effects of cytokines
sending and recieiving cells are distant from each other
what happens when cytokines bind to a receptor ?
initiates a series of reactions that leads to altered gene expression which could effect cell growth and maturation
2 different groups of cytokines
proinflammatory cytokines and antiinflammatory cytokines
proinflammatory cytokines
made by most immune cells and will create an inflammatory response
antiinflammatory cytokines
made by several immune cells and will try to limit the inflammatory response ( activate immune cells that promote healing )
what is inflammation ?
a series of biological reactions in response to a pathogen that has invaded the body
How does inflammation manifest itself ?
Heat, redness, , pain and swelling
what happens in inflammation ?
more blood flow to the impacted area , influx of phagcytic immune cells , removal of forgien antigens anc healing of damaged tissues
order of events of inflammatory response in innate immunity
- Breach, 2. Vasodilation , 3. permeabilization 4. extravasation 5. Phagocytosis
Breach phase
pathogens need to find a breach to enter body, this cold be a wound or cut where the cells get damaged and break through physical barrier
vasodilation phase
increase in the parameter of blood vessel and permeabilization of capillaries which will be induced by vasoactive and chemotactic that will be secreted by damaged tissues and activated immune cells like macrophage and mastcel
redness and heat are a consquence of this process
permiabilzation
increase in capillary permeabiliity from vasodilation, allows for entrance of more fluids to tissues
vasoconstriction of fluids moving away from site and accumulation will create exudate which will contain proteins such as chemokines and complement proteins
extravasation
chemotactic factors released by cells during vasodilation and permeabilization allow more immune cells to be recreuited where neutrophils will arrive via chemotaxis which will then go through extravasation where they will migrate in between capillary endothelial cells
phagocytosis
neutrophils and macrophages and dendritic cells will engulf pathogens ( main method the innate system uses to kill pathogens )
order of inflammatory response
vasodialation, permeabilzation, chemotaxis , margination , extravasation
margination
adhesion of immune cells to endothelial wall of blood vessels
why is heat and swelling needed in the immune response
heat will increase the metabolic rate of cells allwoing themto repair themsleves faster whereas swelling will leak proteins that are needed to clot blood and create scabs and recruit phagocytes
How does innate immunity recognize pathogens ?
Through pattern recognition receptors (PRR)
what is a PRR ?
an integral signalling component of the innate immune system , receptors that are capable of recognizing repeated molecualr patterns of pathogens
what kind of patterns to PRR recognize ?
pathogen associated molecular patterns (PAMPS) which will be expressed either on the surface or found inside pathogens , patterns allow for innate immunity to distinguish itself from non self
major categories that PRRS recognize ?
1) pathogen associated molecular patterns (PAMPS)
2) Danger associated molecular pattern (DAMPS)
What is a PAMP?
molecules associated with groups of pathogens that are recognized by immune cells such as :
Function structures of pathogens
repeated sequences of protein( lipoprotein, glycoprotein , amino acids
examples of PAMPs
lipopolysaccaride
peptidoglycan
flagellin
viral nucleic acids
What are DAMPS
Danger associated molecular patterns which will release molecules by stressed cells undergoing necrosis which are host biomolecules , and indicate damage and inititate inflammation
examples of DAMPS
Abnormal location of cell structure , cell stress indicators molecules
Toll like receptors
class of PRR whose signalling is needed for innate immune response. Will recognize pamps and damps
how are TLRs expressed
depending on type pf PAMP or DAMP, will be expressed on plasma membrane or endosomal/ lysosomal membranes
what happens when TLR are activated ?
initiate transcription for genes encoding for inflammatory cytokines, chemokines and costimulatory molecules which leads to the activation of innate immune cells ( more phagocytosis ) and increase ability to present antigens to adaptive immune system
2 major roles of TLR
1) recognize PAMP or DAMP and
2) induce expression of signalling to activate T cells
signalling process of TLR
1) TLR sense of presence of PAMP or DAMP while bacteria will be engulfed by phagocytosis
2) APC will present pieces of the pathogens ( antigens) on its cell surface through peptide known as MHC complex
3 ) APC will increase costimodulatory production needed to stabilize antigen presenting process
4) naive immunocompetant T cell specific for antigen presented by dendritic cell will bind to MHC complex activating the T cell and adaptive immune response
TLR are a class of ?
PRRs
What is endocytosis ?
A type of endocytosis where cells take up bacteria from environment by invaginating membrane to form a vacuole
2 ways to induce phagocytosis ?
recognition of PAMP through PRR VIA phagocyte or through pathogen opsonzation
steps in phagocytosis
attachment, ingestion, fusion, digestion, release
describe adaptive immunity
second line of defence, requires more time to initiate but will create a specific response against pathogen and produces memory cells in response to reinfection
main characteristics of adaptive immunity
specificity-each cell will recognize one specific epitope of a pathogen
and diversity -composed of countless number of cells to fight any pathogen encountered
components of adaptive immunity
humoral and cell mediated immunity
characteristics of Humoral immunity
B cells which will differentiate into subsets
Charactersitics of B cells
mature in Bone marrow, surface receptor (BCR) act as an antibody factory
subsets of B cells
Plasmocytes and memory B cell
cell mediated immunity characteristics
T cells which differentiate into subsets
Diversity of T cells
CD 4 helper T cell, CD8 cytotoxic T cell,
Memory T cell
Role of T cell
key component of cell mediated response, TCR receptor and mature in the Thymus, help activate immune response and cytotoxic activity
activation of adaptive immune response
APC LIKE dendritic cells that have engulfed pathogens by phagocytosis can present antigens to naive CD4 helper T cells
differentiation in adaptive immune response
TH cells can differentiate into 2 different subsets depending on the antigen encountered
TH1
induces cell mediated immunity
TH2
Induce Humoral immunity
Activation of cell mediated immunity
TH1 cells will activate CD8 cytotoxic T cells and induce there differentiation into CTL ( cytotoxic lymphocyte )
CTL will recognize and eliminate any cells displaying the specific antigen presented at their cell surface by MHC class 1 complex
What are antibodies ?
large Y shape protein which is also known as immunoglobin AB where each antitbody is highly specific and recognizes one epitope
