16-17 - Innate Immunity Flashcards
The defences of the innate immune system can be divided into 3 categories…
- Barriers
- Cellular defences
- Molecular (humoral) defences
Name 4 chemical and physical barriers the body has against pathogens…
- Skin - Mucus membranes - Lysozyme - Stomach acid
Other than providing a physical barrier, name two other features of the skin that protect against pathogens…
- Fatty acids - Comensural bacteria
What is a PRR and where can they be found?
Pattern Recognition Receptors (PRRs) are found on host cells
Name the 3 main types of PRR…
- Toll-like Receptors 2. NOD-like Receptors 3. RIG-I helicase
PAMP stands for…
Pathogen-Associated Molecular Pattern 🚩
On which types of host cell are PRRs present?
- Macrophages - Neutrophils - Dendritic cells
Haematopoeisis is the…
Formation of blood cells
Pluripotent hematopoietic stem cells divide to form two separate cell lineages. These are the…
- Myeloid lineage - Lymphoid lineage
Name 5 innate immune cells derived from pluripotent hematopoietic stem cells…
- Lymphocytes (B, T and NK) - Monocytes - Eosinophils - Basophils - Dendritic cells
Name the 4 cell types derived from the commmon myeloid progenator cells…
- Megakaryocytes (-> thrombocytes) - Erythrocytes - Mast cells - Myeloblasts
Name the 4 cell types derived from myeloblast cells…
- Eosinophils
- Neutrophils
- Basophils
- Monocytes (-> macrophages)
Which 2 types of immune cell engage in phagocytosis?
- Neutrophils
- Macrophages
Problems with phagocytes are generally discovered:
a) Later in life
b) Prenatally
c) Early in life
d) They are generally not discovered
Problems with phagocytes are generally discovered:
a) Later in life
b) Prenatally
c) Early in life
d) They are generally not discovered
Where are neutrophils found in highest abundance?
At sites of high inflammation
Name 3 properties of neutrophils…
- Short-lived
- Multi-lobed nucleus
- Most common phagocyte cell in circulation
________ in the blood become _________ after entering the tissues.
Monocytes in the blood become macrophages after entering the tissues.
Mononuclear phagocytes (e.g. monocytes, Kuppfer cells and alveolar macrophages) are (longer / shorter) lived than neutrophils
Longer
Outline the 5 step process of phagocytosis…
- Recognition
- Endocytosis
- Fusion
- Killing
- Release of digested products
Phagocytes kill pathogens in a variety of ways. This includes…
- Acidic pH
- Antimicrobial peptides such as defensins
- Hydrogen peroxide
- Reactive oxygen species
Oxygen-dependent killing of pathogens by phagocytes relies on a process known as ________ in which NADPH generates _________ which kill bacteria.
Oxygen-dependent killing of pathogens by phagocytes relies on a process known as hexose monophosphate shunt in which NADPH generates reactive intermediate oxygen species which kill bacteria.
Other than phagocytosis, name 3 functions of macrophages…
- Activation
- Secretion of cytokines
- Antigen presentation
Extracellular killing is conducted by which two cells?
- NK cells
- Eosinophils
Which cell type would be responsible for killing an antibody-coated helminth?
Eosinophils
Natural killer cells are part of which branch of the immune system, innate or adaptive?
Innate (they lack antigen specificity)
Natural Killer cells help control infections until adaptive immunity can take over by releasing what substance?
Interferon Gamma (IFNγ) cytokines
Granzyme and perforin are lytic enzymes found in…
Natural Killer cells
Natural killer cells attack which types of cell?
Virally infected (and some tumor cells)
Cytokines link the…
Innate and adaptive immune responses
Cytokines may stimulate or inhibit which 3 processes in cells?
Activity, proliferation and differentiation
Interfereons, lymphokines, interleukins and chemokines are all subgroups of…
Cytokine
Cytokines can be divided into 3 categories based on their functions…
- Mediators and regulators of innate immunity
- Mediators and regulators of adaptive immunity
- Stimulators of haematopoesis
Name 4 key cytokines…
- IL2 (interleukin-2)
- IL1 (interleukin-1)
- TNF-α (Tumor Necrosis Factor Alpha)
- Interferons
Macrophages can secrete cytokines. Name 3 effects of these cytokines…
- Inflammation
- Fever
- Acute-phase response
Excessive cytokine release in a gram negative bacterial infection may lead to…
Endotoxic shock (caused by uncontrolled release of TNFα by macrophage)
Where are blood cells made?
Bone marrow
The balance between microbial symbiosis and dysbiosis in the body is influenced by (3)…
- Diet and lifestyle
- Medicines and hygeine
- Genetics
Innate defences in the gastrointestinal system
The majority of inflammation in Crohn’s disease is found where (and why)?
On the boundary of the cecum/illeum, as this is where the most bacteria are found
Innate defences in the gastrointestinal system
Crohn’s disease is an innapropriate response of the immune system to…
Gut microbiota
Innate defences in the gastrointestinal system
Genetic succeptability to Crohn’s is caused by a mutation affecting the…
NOD 2 receptors
(Sub-type of NOD-like PRR receptors)
Innate defences in the gastrointestinal system
In normal function, what binds to NOD2 receptors, triggering releasing of defensins from gut epitheleal cells?
Muramyl dipeptide
Innate defences in the gastrointestinal system
Release of defensins from gut epitheleal cells helps to maintain homeostasis and prevent…
Overgrowth of gut bacteria (dysbiosis)
Innate defences in the gastrointestinal system
Outline the cause of inflammation in Crohn’s disease…
- Disfunctional NOD2 receptor means defensins are not released to control bacterial numbers
- Bacterial overgrowth occurs
- Damage to the epitheleal barrier leads to cytokine release
- Cytokines trigger inflammation
Innate defences in the gastrointestinal system
Rheumatoid arthritis is an autoimmune disease characterised by which 3 things?
- Synovitis
- Inflammation
- Auto-antibodies
Innate defences in the gastrointestinal system
In mouse models which bacteria was found to cause development of arthritis?
Segmented filamentous bacteria (SFB)
Innate defences in the gastrointestinal system
In the mouse model of autoimmune arthritis, SFB leads to an increase in which cell type, with what notable effect?
Increase in TH17 cells leads to increased IL-17 synthesis leading to increased inflammation
Despite traditionally being seen as a sterile environment, sequencing has shown the presence of commensural bacteria in the urinary tract. They are mostly which genus?
bacillus
UTIs are the 2nd most common infection in the world. They are most commonly caused by which bacteria (and from where)?
Uropathogenic E. Coli from the gut
Uropathogenic E.Coli (UPEC) are flagellated, thus capable of locomotion. As a result they may also infect the bladder and kidney. These infections are known as…
Cystitis and pyelonephritis, respectively
Three factors which help to maintain a healthy urinary tract are…
- Urine flow
- Epitheleal barrier
- Epitheleal defensins
The urinary tract detects flagellated bacteria via which receptors?
TLR5
(extracellular Toll-like receptors)
Defective TLR5 recepetors in ~10% population is responsible for a genetic predisposition to UTIs
