Innate Immunity
mercoledì 4 novembre 2020
16:25
Innate immune response : Cells are not specific , fast response(min-h), No memory
Adaptive immune response, chemical barriers, Lysozymes, Low pH, Physical barriers, Epithelium, Cilia
Pathogen gets in, Macrphage (the garbage truck of tne body) gets into action, eat also dead cells, eat also
invading pathogen, recognizd pathogens quickly within minutes of infections, molecules that it's has on the
surface, Don't distinguish one invader from another, coz pathogens have molecules (PAMPS) that human
don't have, ex. On the Bacterial Wall, Lipoteicoic acid, Peptidoglycan, Lipopolysaccharides(LPS) and Fungal
wall components: Mannan and Flagella Proteins, and may include viral RNA/DNA. PAMPS is recognized by
Pattern recognition receptor (PRRs), found on various immune cells like (macropaheges, neutrophils,
eosinophils, basophils, mast cells); 2 group of PRRs : Phagocytic PRRs, bind to pamps and can eat pathogen,
do not release cytokines, if there are few they get activated and for (phagosome+Lysosome =
Pahagolysome); they will undergo a variety of reactions: The Phagolysosome contain 2 types of Granules,
Specific granules and Azurophilic granules and SIGNALING PRRs
How does phagolysosome work: contain 2 type of granules: 1) Specific Granules - work 1st; contain Proteases
and Hydrolyses and activate at Neutral pH. K+ and H+ ions get to work and lower pH, Azurophilic Granule
enzymes start work) ; Enzymes kill about 2% of pathogens it's eat, other 98% is killed by a process called
Oxidative or respiratoty brust. -- Destroys the phagolysosome and the macrophage.
Phagocytes, Macropahges and Neutrophils (The Best) are capable of OXIDATIVE BURST, leaves the production
of Nitric Oxide + Raective O2 Species. (Unstable/Contains), Superoxide anions and Hydrogen Peroxide. Bind to
molecules in the cell and that's lead to tissue Damage.
The Oxidative Burst, Phagolysosome forms (Activates NAPDH OXIDASE), transfers electron, superoxide
dismutase forms Hydrogen Peroxide (Which is highly oxic microrganism)
Also in the presence of NADPH and O2, arginine forms NO. Inducible nitric oxide Synthase (INOS).
NO + reactive O2 Species, destro pathogens (& Phagocyte). NADPH oxidase Deficiency- Pathogen escapes and
create Chronic Granulomatous Disease (CGD).
Signaling PRRs and Phagocytic PRRs, request reinforcement, stimulate release of cytokines, small secreted
proteins that the cell use to communicate with each other. The most important group is the TLRs, is Single
polypeptide chains, Found On : All leukocytes, epithelial cells and Endothelial cells.
TLRs :
1,2,4,5 & 6 are bind on the Cell Surface and Bind to PAMPs : (Peptidoglycan, Lipopolysaccharide, Flagella)
3, 7, 8 & 9 are present in Cell and Bind to Intracellular PAMPs, like viral RNA, Activate Transcription factor (NFKB); activates Proinflammatory Cytokine Secretion IL-1B, TNF-a, IL-6. These cytokines cause Vasodilation +
Leukocytes and Fever.
Intracellular Cell Secretes:
Interpheron alpha, interpheron Beta (Interfere with the virus's ability to replicate).
Phagocytic PRRs : help pahgocytes ingest pathogens, destro Pathogens (Specific and azurophilic granules or
respiratory Burst)
Signaling PRRs (TLRs) : Bind to surface/ Intracellular PAMPs, Stimulate cytokines Production (Calls more
immune cells)
Nuova sezione 2 Pagina 1