Innate- Diebs Flashcards
What are the 4 main functions of the innate immunity?
- complement activation
- inflammation
- Cell activation
- Priming of adaptive immune response
What are 2 function of macs?
- phagocytosis
2. expresses MHC molecules and acts as an APC
Does the innate immunity depend on the recognition by lymphocytes to function?
No
What are 3 molecular non self motifs that the innate immunity recognizes?
- PAMPs
- DAMPs
- Absences of SELF marker molecules
- 1 and 2 are phagocytosis
What is the cytoplasmic domain of hetero/homodimerized TLRs? Their function?
TIR domain
- recruitment of adaptor proteins
What is the function of TRLs?
Recognize PAMPs and signal gene transcription events to combat foreign material. They DO NOT cause phagocytosis
Are neutrophils APCs?
NO
- but dendritic cells and macs are
What are the evaginations of phagocytes called around a microbe?
Pseudopodia
A defect in NADPH phagosome oxidase cause which disease?
Chronic Granulomas disease
- recurring infections before the age of 5 and after
- due to a X-linked recessive mostly
- decrease in bodies reactive species in lysosomes
What are the most common suspects for causing chronic infections in a person with chronic granulomas disease?
CATs Need PLACESS to Belch their Hairballs
- Catalase +
- Nocardia
- Pseudomonas
- Listeria
- Aspergillus
- Candida
- E Coli
- Staph
- Serratia
- B cepacia
- H pylori
What is the test to confirm chronic granulomas disease?
Abnormal dihydrorhodamine (flow cytometry) test. A decrease in green fluorescence
What are some ways that opsonization make microbes more tasty?
Coat in CRP,
- Antibodies
- Mannose binding lectin
What are opsonins?
Phagocytosis enhancing proteins
- soluble proteins that have bound the the surface of microbes
- indirect phagocytosis
- AKA- Soluble pattern recognition proteins
What do opsonins bind to?
Many of them bind to repeating components like:
- carbohydrate structures
- lipopolysaccharides
- viral proteins
What are some membrane opsonin receptors on phagocytes?
MBL and C1q (like FC region on antibody)
- structurally similar
- all bind CD91 opsonin receptor on phagocyte to activate
What is the complement system and its goal?
Group of 20 serum proteins which try to control inflammation
- act as a amplifier
What are the 3 ways which complement can act?
- lysis
- Chemotaxis
- Opsonization
What is the classical activation of complement?
Activated by antibodies or mannose binding lectin
- C1q bind to Ab/Ag complex
- cleaves and activated downstream complement response
- C5b bins to membrane associated with Ab/Ag complex and forms the membrane attack complex
What is the alternative pathway of complement activation?
Activated by by microorganisms spontaneously
- acting as a part of innate response
- C3 is spontaneously cleaved to C3b Which then binds to bacterial and yeast cells walls as well as virus envelopes
- Leads to downstream activation of complement components
What physiological changes can happen after complement activation?
- Increased blood flow
- Increased permeability
- Release of inflammatory mediators fro mast cells
What are the 3 pathways of which complement can be activated?
Classical
Lectin
Alternative
What is the lectin pathway of complement?
Mannose Binding lectin bound to bacteria carbs mimics C1q.
What is the function of the a complexes of complement? Ex C3a/C4a/C5a?
Act as chemoattractants to increase directional migration of PMNs and macs
- activate PMN and macs degranulation
- cause mast cells and basophils to degranulate (histamine)
- 5>3>4
what is the function of b complexes of complement like C3b or C4b?
Deposited on any surface with exposed amine or hydroxyl
- opsonins
- cleave more C3
What inactivated complement on our cells?
Decay accelerating factor (DAF)
- AKA CD55
- Cl esterase inhibitor
what inactivates the Membrane attack complex?
CD59- Protectin
Homologous restriction factor (HRF)
What are the hallmarks of Inflammation?
Edema
Hyperthermia
Local Hypoxia
Extravasation (WBC’s)
What cytokine recruits neutrophils?
IL-8
What are 3 things that trigger inflammation?
Complement C5a
Macs
NK cells
What does complement 5a activate?
Histamine
Prostaglandin E2
Leukotriene D2
Leukotriene D4
What does prostaglandin E2 cause?
vasodilation and increase vascular permeability
What do Leukotrienes D2/4 cause?
Neutrophil chemotaxis, increased vascular perm
- increase vascular perm
What doe macs call to action?
TNF- fever and E-selectin expression
IL-1- Local inflammation
IL-8- Chemotaxis
What do NK cells recruit?
INF-y - activation of phagocytic cell and other NK cells
What are 3 priniple changes in tissue during acute inflammation?
- Increased blood supply to affected area
- increased cap perm
- Increase leukocyte migration in to the affected area
What is the principle description of chronic inflammation?
Persistent antigenic stimulus and cytotoxic effects of the unresolved infection
What the prevalent cells in acute inflammation and chronic?
Neutrophils and helper T cells
- Macs, cytotoxic T cells and b cells in chronic inflammation
What comes into contact first with a pathogen in the body?
Resident phagocytic cells like dendritic cells or macs
- Then neutrophils are the first responders called onto the scene
What are the important pro-inflammatory cytokines?
TNF-a
IL-1
IFN-y
Where is leukocyte migration most likely in the blood stream?
Venules - largest and least amount of flow (shear)
What is E-selectin and what does it bind?
It is an endothelial binding protein that binds CD15 on immune cells.
- Tethering
- there is always a small amount of tethering going on at all times.
What are the 3 steps of leukocyte adhesion?
- Tethering- E-selectin
- Triggering via chemokines from site of infection
- Adhesion via activation of integrins like ICAM-1 (endo) and CR3/LFA-1 on cell
What doe tissue cells do for the immune system, whats their purpose?
Provide a barrier
- if infected of damaged signal for help via interferons/chemokines
- Also produce defensins and cathelicidins to fight against microbes
What are the signals (cytokines) for differentiation of polymorphonuclear neutrophils (PMNs)?
IL-3 + GM-CSF–> IL-3+ GM-CSF+ G-CSF
What are the signals (cytokines) for differentiation of Eosinophils?
IL-3 + GM-CSF–> IL-3+GM-CSF+ IL-5
What are the signals (cytokines) for differentiation of basophils?
IL-3+GM-CSF–> IL-3+GM-CSF+IL-4
What are the signals (cytokines) for differentiation of Monocyes
IL3+GM-CSF–> IL-3+GM-CSF+M-CSF
What are the signals (cytokines) for differentiation of Macs?
IL-3+GM-CSF–> IL-3+GM-CSF+M-CSF–> GM-CSF+M-CSF
What are the signals (cytokines) for differentiation of dendritic cells?
IL-3+GM-CSF–>IL-3+GM-CSF+M-CSF–>GM-CSF+IL-4
What are the signals (cytokines) for differentiation of NK cells?
IL-7–> IL-2
What are some facts about PMNs?
Contain granules that dont stain with acidic or basic stains
- fuse with granule to form phagolysosome
- Can kill by antibody dependent cellular cytotoxicity
What are some facts about eosinophils?
Contain Major Basic Protein (MBP)
- activated by C5a and C3a to degranulate
What is the purpose of MBP?
potent toxin for helminths
- induces histamine release from mast cells
- activated neuts and platelets
- can provoke bronchospasm
What are some facts about basophils?
- Activated by C5a and C3a to degran
- release histamine when IgE cross linked
- Express FCeR1 for IgE and thus can have IgE on surface
What are some differences between basophils and mast cells?
Mast cells are not found in circulation
- Mast cells last weeks/months rather than days
- MC have proliferative capacity
- MC mature in the connective tissues
What are some cytokines that macs produce?
I-NF-a
-IL-1B, IL-6, TNF-a (Fever)
CXCL8 (IL-8) chemotactic factor
- IL-12
What is a classical dendritic cell?
Eats and presents (APC) to T cells
What is a follicular dendritic cell?
Passively present foreign Ag in the form of immune complexes to B-cells in lymphoid follicles
What are the 3 APC’s and what do they express?
DC, Mac, B-cell
- MHC II thus interact with CD4
- They also have MHC I because all cells express this
What are some facts about NK cells?
CD16 and CD56 are important markers
- recognize damaged cells and deficiency in MHC Ag
- activated by INF-y
- IL-12 and TNF-a activated
What is severe congenital neutropenia?
- Lack in ability to produce or maintain a normal level of neutrophil
- leads to frequent bacterial infections
What is Chediak-Higashi syndrome?
Defect in Gene LYST a lysosomal trafficking gene that affects lysosomes and melanosomes
- increase susceptibility to bacterial infections
- autosomal recessive
- Microtubule dysfunction in phagosome-lysosome fusion
What is Leukocyte adhesion deficiency?
Lack of LFA-1 integrin (CD18) protein on phagocytes
- Inability to recruit innate immune cells to site of inflammation
- increase susceptibility to bacterial, fungal and viral infections
- autosomal recessive
What is significant on the findings of an individual with LAD (leukocyte adhesion deficiency)?
- No pus formation
- Impaired woud healing
- Delayed separation of umbilical cord >30 days
- increased neutrophils but absent at site of infection (why there is no pus formation)
What are some significant findings in an individual with suspected Chediak-Higashi syndrome?
- Recurrent pyogenic infections by staph and strep
- Partially albino
- peripheral neuropathy
- progressive neurodegeneration
- Infiltrative lymphohistiocytosis
- giant granulocytes and platelets
- Pancytopenia
- Mild coagulation defects
What is infiltrative lymphohistiocytosis?
hyperinflammation caused by uncontrolled proliferation of activated lymphocytes and macrophage
- proliferation of morphologically benign lymphocytes and macrophages that secrete high amounts of inflammatory cytokines
- can cause cytokine storm
what are some common microbial ligands?
Mannans B-Glucans LPS LTA (Lipoteichoic acid) Lipopeptides Diacylglycerides
What binds to mannans?
Mannose receptor
DC-SIGN
What bind to B-glucans of fungi and some bacteria?
Dectin 1
What binds to LPS and LTA of bacteria?
SR-A or scavenger receptors
What does SR-B scavenger receptor bind to?
LTA, Lipopeptides, B-glucans and diacylglycerides
What is the main source of histamine and what is its action?
Mast cells and basophils
- increased vascular perm and smooth muscle contraction
- chemokinesis
What is the main source of serotonin and what is its action?
Platelets and mast cells
- increase vascular perm
- smooth muscle contraction
What is the main source of Platelet activation factor (PAF) and what is its action?
Basophils, neuts and macs
- Mediator release from platelets
- increase vascular perm
- smooth muscle contraction
- neuts activation
What is the main source of IL-8 and what is its action?
Mast cells, endothelium, monocytes and lymphocytes
- polymorph and monocyte localization
What is the main source of C3a and what is its action?
Complement C3
- mast cell degran and smooth muscle contraction
What is the main source of C5a and what is its action?
Complement C5
- mast cell degran, neuts and macs chemotaxis
- neuts activation
- smooth muscle contraction
- increase capillary perm
What is the main source of bradykinin and what is its action?
Kinin system (kiniogen)
- vasodilation
- smooth muscle contraction
- increase capillary perm
- pain
What is the main source of prostaglandin E2 and what is its action?
Cyclo-oxygenase pathway and mast cells
- vasodilation, potentiates increase vascular perm
What is the main source of leukotriene B4 and what is its action?
Lipoxygenase pathoway and mast cells
- neuts chemotoxis
- synergizes with PGE2 in increasing vascular perm
What is the main source of Leukotriene D4 and what is its action?
Smooth muscle contraction
increasing vascular perm
What is the main source of Fibrono-peptides and fibrin breakdown products and what is its action?
Clotting system
- increase vasuclar perm
- neuts and macs chemotaxis