Factors & Components of innate immunity, General terms Flashcards Preview

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Flashcards in Factors & Components of innate immunity, General terms Deck (19):
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Complement system (humeral/soluble component of innate IS)

- system of plasma protein with enzymatic function activated in a cascade manner

- Participates in:
○ opsonization (enhanced phagocytosis)
○ inflammation
- labels pathogens for further destruction (cytolysis: destruction of cell)

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Cytokines (humeral/soluble component of innate IS)

Def: small soluble molecules that serve as mediators in and between immune cells or other organs
- act via specific receptors
1. Interleukins (ILs)
2. Interferons (IFN - alpha, beta, gamma): used as treatment of viruses
3. Colony-stimulating factors
4. Tumor-necrosis factors (TNF)
5. Transforming growth factors (TGF)

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Macrophages (cellular component of innate IS)

- attack pathogens directly without preliminary contact
- exist regardless of a present pathogen (Abs exist only in case of an already penetrated pathogen)

Two basic roles in innate immunity:
- phagocyte recognised pathogens, send signals to animate other cells and initiate adaptive immunity
- release soluble mediators(=cytokines), wh. assist in inflammation

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Pattern-recognition receptors (PRR)

- proteins, (mostly) expressed by cells of innate IS

- these cells are: Macrophages, dendritic cells, NK-cells, mast cells, neutrophils cells

- Toll-like receptors (TLRs) a class of PRR wh. recognise the pathogen by means of Pathogen-Associated Molecular Patterns(PAMPs) and regulate activity of genes

- PAMPs are structures located in or on pathogens (e.g. bacterial carbohydrates: lipopolysacharide, mannose // nuclei acids: bact./viral DNA orRNA)

- Due to TLRs the innative IS can distinguishes btw “self” and “non-self”

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1. Phagocytosis (Factor of innate immunity)

It ends with:
- complete degradation of foreign engulfed pathogens/agent
- incomplete degradation — antigen processing
- it is nonimmune (=factor of innate IS) and immune

Opsonization (= enhanced phagocytosis):
- coating of pathogens with molec.(antigens), thus enhancing phagocytosis of pathogens

Opsonins (= enhancing factors)
- complement system, antibodies and some proteins

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2. Inflammation (factor of innate immunity)

- a defense reaction induced by exogenous and endogenous factors
- initiated by reaction of macrophages against pathogens
- symptoms: rubor(redness) , tumor(swelling), calor(heat), dolor(pain) and functiolysis( loss of function)

Changes in blood vessels:
- increased diameter( =vasodilation)
- expression of adhesion molecules
- increased permeability

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3. Mechanical barrier (Factor of innate immunity)

- vaginal, respiratory and gastrointestinal mucosa (protect hollow organs)
- washing out/ eliminating of activity of secretions (saliva, tears, urine, sperm, vomiting and diarrhoea)
- cilia in respiratory and intestinal mucosa, hairs in nostrils cause that pathogens do not attack the body (by sneezing or coughing)

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4. Chemical barrier (Factor of innate immunity)

- sweat and gastric and bile juice (have acidic pH-value -> destroy pathogens)
- hydrolytic enzymes saliva
- proteolytic enzymes in small intestine
- nonpathogenic microorganism in large intestine

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5. Physiological barrier (Factor of innate immunity)


- increase of body temperature and 02-pressure
- hormonal balance ( corticosteroids — hormones, important for immune diseases)
- Peristalsis (Bewegungsmuster von Hohlorganen z.b. Darm, welleförmige, Regenwurm artige Bewegung)

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Antigens

Def: is an antibody generator: a molecule with endogenous or exogenous origin capable of specific binding to an antibody or to an cell receptor (Ab) or lymphocyte receptor
- are high molecular weight substances - above 10 kDa

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Epitope

Epitope: part of the antigen molecule which binds specifically to a paratope of the antibody or a specific lymphocyte receptor

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Haptens

Haptens:
- low molecular weight substances which can elicit immune response only when attached to a large protein carrier
- are not antigens because cannot induce an immune response, but can bind to Abs and immune cells
- enter blood and bind to larger blood proteins and start to act as antigen
- most drug induced allergies and side effects are due to haptens, f. ex. penicillin, aspirin etc. can act as haptens

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Characteristics of the antigen

- foreign origin
- specificity
- antigenicity
- immunogenicity

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Foreign origin (characteristic of antigen),

○ product of a foreign genotype or of altered self-genetic information (mutations, infected, aging)
○ immune cells are educated to recognize self from non-self-molecules during the embryonic period
○ Immunologically privileged sites (see next card)

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Immunologically privileged sites (part of foreign origin)

○ Immunologically privileged sites:
!NB: white matter in brain, eye-lens, testicls, thyroid gland, suprarenal glands

- Lymphocytes do not enter these zones
- local cytokines are produced and leave these zones
together with autoantigens and prevent destructive immune response
- cells express Fas-ligand which binds to incoming T-Ly, having Fas-receptors -- leads to apoptosis of intruding Lymphocytes

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Specificity: (characteristic of antigen)

Specificity:
○ is defined by the epitopes of the antigen

○ specificity is not absolute because of cross reactivity: ability of antibody produced against to react with different Ag-molecules having similar epitopes

○ first generation of antibodies produced is not very specific, generations grow more specific with time

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Antigenicity (characteristic of antigen)

Antigenicity:
- def: capacity of the Ag to react to a different degree with the Abs and immune cells produced against it

- quantitative quality which measures intensity/strength of immune response

- measured by amount of Abs and immune cells produced against Ag

Immunedo................

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Immunogenicity

Immunogenicity
- capacity of the Ag to induce specific, strong and long lasting immune response: ability of the AG to induce the production of memory cells

- duration of immune response
- depends on chemical structure, degree of foreignness of molecule etc.
- f.ex. low immunogenicity: dysentery bacteria (you can get them several times in life)
- f.ex. high immunogenicity: viruses causing measles, chicken pox (lifelong immunity)

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Classification of antigens

- autoAgs: derived from same individual -> stimulates auto-antibodies in organisms where they are produced

- alloAgs: delivered from different individual of the same species -> stimulates production of Abs in those where they lack (isoantigen)

- heteroAgs: delivered from diff. species (has greatest immune response) ->able to stimulate immune response in other species

- organ, tissue, cell-specific Ags
- stage-dependent Ags - oncofetal