Factors & Components of innate immunity, General terms Flashcards
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)
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)
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
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”
- 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
- 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
- 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)
- 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
- 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)
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
Epitope
Epitope: part of the antigen molecule which binds specifically to a paratope of the antibody or a specific lymphocyte receptor
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
Characteristics of the antigen
- foreign origin
- specificity
- antigenicity
- immunogenicity
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)
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
