Innate immunity Flashcards
What are the three levels of defense?
Level 1: Skin, mucous membranes, stomach acid, cilia, lysozyme in tears,
Level 2: Macrophages, neutrophil.s, eosinophils, basophils, monocytes
Complement system
Level 3: Adaptive immunity
Cellular (cytotoxic)
Humoral( Antibodies)
Which immunity has a fast nonspecific response, and has no memory?
innate immunity
List the cardinal signs of inflammation
Swelling (tumor)
Pain (dolor)
Redness (rubor)
Heat (Calor)
What are the causes of inflammation
Injury
Pathogen
Chemical or radiation
What are the important role players of inflammation?
Microvasculature
Circulating blood cells
Immune cells n tissue
Cytokines (e.g. histamine and prostaglandins)
State function and location of mast cell
Mast cell: Secretes cytokines (e.g. Histamine, Heparin). Dilates BVs, starts the inflammatory response. Found in CTs and mucous membranes.
State function and location of macrophages
2.Macrophages: Phagocytic and stimulates response of other immune cells. Migrates from BVs into tissues.
State function and location of Natural killer cells
3.NK cells: Kills tumor cells and virus-infected cells. Circulates in blood and migrates into tissues.
State function and location of dendritic cells?
4.Dendritic cells: Antigen-presenting cell, thus it triggers adaptive immunity. Found in epithelial tissue, but migrates to the lymph nodes when activated.
State function and location of monocytes
5.Monocyte: Differentiates into macrophages and dendritic cells in response to inflammation. Stored in spleen, moves through blood vessel to infected tissue.
Function and location of neutrophil
- Neutrophil: First responder at the site of infection or trauma. Releases toxins that kill or inhibit microorganisms. Recruits other immune cells to the site of infection. Migrates from blood vessels into tissues.
Function and location of Basophil
- Basophil: Responsible for defense against parasites. Releases histamines that cause inflammation and may be responsible for allergic reactions. Circulates in blood and migrates to tissues.
Function and location eosinophils
8.Releases toxins that kill bacteria and parasites by also causes tissue damage. Circulates in blood and migrates to tissue
Name the surveillance cells located in circulation
Neutrophils
Monocytes: Differentiate into macrophages at tissue
Name surveillance cells located in tissues
Resident macrophages
Mast cells
How does the immune system know when the body is under attack?
The immune cells have PRRs (Pattern Recognition Receptors) which detect PAMPs (Pathogen Associated Molecular Patterns) which are found in invading pathogens
What are toll-like receptors and how do they work?
BINDS LIGAND
Toll like receptors are proteins found on the cell membrane and vesicles of immune cells. They are stimulated by different things found in the pathogen, e.g. flagellum.
When these receptors are activated, they send signals to the nucleus to activate a gene for the production of cytokines such as interferons, Interleukin 1, Tumor necrotic factor, etc. This enhances inflammation by:
Increasing phagocytosis
Increasing costimulatory molecules
Increasing immune cell migration
increasing antigen presentation
What are NOD-like receptors?
They are receptors found on the inside of the cell (in the cytoplasm) and they pick up signals from inside the cell.
-They have similar outcomes as TLRs
TLRs and NLRs —-> Inflammasomes—–> Caspase 1——> Release of mature cytokines (IL-1 and IL-8)
Name the inflammatory mediators
(TAKE ACTIVE PART ON RESPONSE TO INFLAMMATION)
Neutrophils and macrophages: cytokine release—–> recruitment and activation of other WBCs
Liver: Releases C reactive proteins for the complementary system
List and state function of cytokines
Colony-stimulating factors: development and differentiation of immune cells from bone marrow precursors.
Interferons (IFN): IFN-α and IFN-β inhibit viral replication, IFN-γ regulates immune responses
Interleukins (IL): Communication between leukocytes.
Tumor necrosis factor (TNF) family: Mixed collection of cytokines, promote inflammation (TNF-α and TNF-β), stimulate osteoclasts and bone resorption (osteoprotegerin).
Chemokines: cell movement in response to chemical stimuli
How do interferons work?
- They signal uninfected cells to destroy RNA and reduce protein synthesis.
- They signal neighbouring infected cells to undergo apoptosis.
- They activate immune cells
What are the main functions of interferons?
- Inhibits viral replication
- Tumor surveillance
- Alter expression of all cells to be resistant to infection
What stimulates diapedesis?
Histamines and leukotrines produced by mast cells.
Describe the process of phagocytosis
Neutrophils —-> form pseudopodia —-> encloses particle in chamber—–> forms phagosome
Macrophages —–> more powerful phagocytes —–> digest particles and extrude residual particles
Lysosomes digest engulfed particles
What is in a phagosome?
Proteolytic enzymes
Lipases (macrophages)
Bactericidal agents
Oxidizing agents – superoxide, hydrogen peroxide, hydroxyl ions
Where are resident macrophages found?
Skin and subcutaneous tissue Lungs (alveolar macrophages) Liver sinusoids Spleen and bone marrow Lymph nodes
Describe the process of inflammation
Vasodilation of local blood vessels
Increased permeability of the capillaries, allowing leakage of large quantities of fluid into the interstitial spaces
Clotting of the fluid in the interstitial spaces because of increased amounts of fibrinogen and other proteins leaking from the capillaries
Migration of large numbers of granulocytes and monocytes into the tissue
Swelling of the tissue cells
Walling off –immediate effect via fibrinogen clots
1st line defense – resident macrophages (1st hour)
2nd line defense_ Neutrophil invasion – first few hours
3rd line defense- Secondary macrophage invasion – several days, monocytes need 8 hours to mature in tissue
4th line defense- Bone marrow takes 3-4 days to synthesize new granulocytes
Define chemotaxis
Movement of an organism in response to a chemical stimulus
Describe how neutrophils migrate from the blood vessels to the tissue
Cytokines: TNF an IL-1 Adhesion molecules: Selectins and ICAM-1 Integrin on neutrophils – bind (margination) Capillaries become “leaky” – diapedesis Chemotaxis
Describe pus formation
Necrotic tissue Dead macrophages and neutrophils Tissue fluid Tissue eventually autolyzes End products abdorbed into lymph and surrounding tissue
List the cells involved in allergy formation
Basophils (in circulation) Mast cells (tissue resident) Histamine and Heparin Propensity for IgE Release eosinophil chemotactic factor
Eosinophils – parasitic infections
Collect in peribronchial tissues during asthma
Functional cells in innate
Granulocytes, macrophages, mast, dendritic, natural killer
(EXCEPT T and B cells)
Difference between toll-like and nod-like receptors
Toll-like: inside,cell membrane
Nod-like: inside,cytoplasm
Interleukins released by TLR and NLR
IL1 and IL8
Results after the release of cytokines (IL1 and 8)/ what does cytokines enhance
increased phagocytosis
cell migration
antigen presentation
stimulatory molecules
Inflammation during chemotaxis
In response to a cut;
1. Mast cells release histamine (COULD ALSO E OTHER MEDIATORS, CYTOKINES) which cause
2. Dilation of blood vessels
3.Neutrophils and monocytes leave a cell
4. Monocytes mature to macrophages
5.Macrophages phagocytisise
6. Neutrophils invade
7.COMPLEMENT SYSTEM (opsonization)
8. Dendtritic cells
Defense of inflammation
- Resident macrophages
- Neutrophil invade
- Secondary macrophage
- Granulocytes and monocytes
Resident macrophages
Skin
Alveoli
Liver sinusoid
Spleen
Bone marrow
Neutrophil invasion cytokines
TNF and IL-1
Adhesion molecules of neutrophil invasion
CAM1 and selectin
Main cells for innate immunity (inflammation)
SURVELIANCE
Mast cells
Macrophages
Neutrophils
Monocytes
