Immunology Flashcards
what are the 2 types of immunity?
- innate (first and second line of immune response - relies on mechanisms that exist before infection
- Adaptive immunity - third line - relies on mechanisms that adapt after infection
Describe innate immunology? (6)
it includes physical and chemical barriers, and responses.
- It is present at birth in all individuals& based on genetics
- It relies on already formed components
- Rapid response
- Non specific so the same molecules respond to a range of pathogens
- It has no memory so the same response after repeated exposure
what is the first line of defence in innate? - examples
skin, ciliated cells, lysozyme, coughing, sickness
Give examples of 2nd line of defence innate
blood clots, histamine release by mast cells, leukocytes
Describe the physical barriers in innate response
SKIN- physical barrier and prevents Passage of microbes- it is acidic and acidity prevents passage. The surface of the skin provides good bacteria that can outcompete pathogens
RESPIRATORY- line with ciliated `cells and a layer of mucus - mucus traps the invading microbes and debris, cilia remove particles.
- STOMACH- acidic pH in stomach and digestive enzymes remove and destroy foodborne pathogens
What are humoral components of the innate immune?
Lysozymes and the complement system (group of proteins found in blood plasma). They complement proteins that work with antibodies.
- Mediate the lysis of microbes and mark them for phagocytes, cause inflammation and stimulate mast cell release of histamine.
What are the cellular components of innate? (7)
- mast cells
- basophils
- neutrophils
eosinophil - macrophage
- dendritic cell
- NK cell
Function of mast cells
release histamine
Function of - basophils, eosinophils and neutrophils?
granulocytes - WBC with granular staining, release - digestive enzymes, histamine and heparin
Function of macrophage & dendritic cells
Phagocytes - engulf pathogens and destroy, and release cytokines
Function of NK cell
recognise & kill infected host cells
what do macrophages and dendritic cells do?
express pattern recognition receptors - these recognise bacteria, fungi, pathogens, dsRNA (viruses), bacterial DNA
What do the pattern recognition receptors do?
mediate the activation of a transcription factor - NF-Kappa B
What does NF-Kappa B do?
activates transcription and release of cytokines
what are cytokines?
regulatory proteins secreted by WBC
what do cytokines do?
Bind to specific receptors on target cells triggering signal transduction pathway & altering gene expression.
Types of cytokines
pro inflammatory which stimulate an immune response, or anti inflammatory which inhibit the immune response
Give example of an important cytokine
TNF - pro inflammatory cytokine
what does the cytokine TNF do?
mediates a feed forward loop - activate cells with TNF then activate NF-kappa B leading to production of more pro inflammatory cytokines.
- Inflammation activated in more cells to eradicate infection
what are the 5 hallmarks of inflammation?
- Rubor (redness)
- Dolor (pain)
- Calor (heat)
- Tumor (swelling)
- Function lease - loss of function of organs or tissues involved
what are the characteristics of adaptive immunity?
- slow response during the first infection but very fast in secondary infections
- has memory and is specific
- involves antibodies
- 2 types- humeral and cell mediated
- basis of all vaccines
what is the cell mediated mechanism in adaptive
eliminates intracellular microbes that survive within phagocytes/cells
what is the humoral mechanism in adaptive
mediated by antibodies- eliminate extracellular microbes and toxins.
what do antibodies do?
recognise antigens (toxic)
define an antigen
a toxic or foreign substance which induces an immune response especially production of antibodies
characteristics of antibodies
membrane bound or soluble
Y shaped or T shaped polypeptides
belong tot he gamma-globulin fraction of serum proteins
2 identical heavy chains, 2 identical light
what contains antibodies?
B cells
what do antibodies do ? (functions)
- bind to antigens…
- inflammation
enhance phagocytosis by coating antigen
block adhesion of bacteria and viruses to mucosa
cell lysis
Significance of major histocompatibility complexes?
Receptors attach to membrane - important in the recognition of self & non self cells (2 types - MHC1 and MHC II)
MHCI receptors?
presents part of our own proteins to cytotoxic T cells (own cells).
- Mutated cells e/g cancer and viruses co not regulate expression of MHCI and don’t present proper proteins so can tell which are which
MHC II receptors?
Presentation of antigens (non self) to immune system - present to T helper cells - pathogen
what cell type produces antibodies in response to a pathogen?
B cells
What are B cells?
Naive B cells move throughout body & includes antigen specific antibodies. When it encounters an antigen it divides to become either a memory B cell, or a plasma B cell (effector) to produce antibodies
what are the 2 types of T cell?
- Cytotoxic T cell (induce infected cells to kill selves) - CD8+ cells
- T helper cells (assist other cells e.g maturation of B cells, activate cytotoxic T, macrophages) - CD4+ cells
what can T cell receptors only recognise?
antigens bound to MHCI or II
Describe phases of adaptive immune response
- Antigen presenting cell - induces clonal expansion of B and T cells
- differentiation of T and B into effector cells followed by elimination of antigen - via cell mediated or hour immunity
- No longer need immune response so must turn it off - via apoptosis. But do have some surviving memory cells - memory B and cytotoxic T
when is the adaptive immune response triggered?
when a macrophage delivers an antigen to a T helper cell
what does a vaccine do?
Provides adaptive immunity - introduce a toxic (resembles toxin) - formation of memory cells & short activation of immune system.
- Should we be exposed by the same antigen again, there is fast & strong activation of immune system so body can get rid of pathogens before symptoms occur
what do vaccines stimulate production of?
Memory cells
what are the 2 things that happen when the immune system goes wrong?
- Hypersensitivity
2. Immunodeficiency
what is hypersensitivity and give examples
Causes cell damage through excessive immune response to antigens.
- Overreaction to infectious agents
- Allergy - overreaction to environmental stimuluses
- autoimmunity- overreaction to self
what is autoimmunity and allergies?
allergy – overreaction to environmental substances
autoimmunity – overreaction to self
what is immunodeficiency?
loss of function of components in immune system - occur in any part or state and cause the person to become prone to infection (high risk).
- Can be due to genes e.g congenital ID (SCID)
- Can be acquired e.g aids
why do pollen allergies get worse every year for some people?
Memory cells cause a stronger reaction
In adaptive defences - what are the types and cells involved?
- Humeral immunity - B cells
2. Cellular immunity - T cells
in innate defences - what are the types and cells involved?
- Surface barriers - skin, mucosal membranes
2. Internal defences e.g. phagocytes, fever, NK cells, antimicrobial proteins & inflammation
