Innate Immunology Flashcards
Functions of immune system
- Protect from pathogens and foreign molecules
- Remove dead or damaged cells
- Attempts to recognize and remove abnormal cells- bacteria, cancer, infected
What can go wrong with immune system function
Incorrect response- autoimmune disease (type I diabetes- recognize part of u as bad)
Overactive responses- allergies (overreact to something that isn’t naturally harmful)
Lack of response- immunodeficiency disease (HIV)- immune system can’t launch a response
Lines of defence
- Physical- skin, mucous membranes (nasal and oral cavity- spit out, stomach- acidic), antimicrobial, substances (excrete in sweat and oil)
- Inflammation (redness, heat, swelling, pain, increase blood flow to area to deliver immune cells), fever (inc body temp, inc immune activity), phagocytes (break down, ingest invader)
- Humoral (antibodies) and cellular immunity (specific T/B cells)
Innate vs adaptive lines of defence
Lines 1/2- innate
Line 3- adaptive
What is GALT
Gut associated lymphoid tissue
Screen digestive for invading bacteria
Role of lymph vessels in immunity
Uptake extra fluid, blood
Check if bad stuff in contents via lymph nodes
Lymph nodes- house immune cells that can spot and get rid of bacteria
Drain back into circulation at subclavian veins
Where are most blood cells produced
Red Bone marrow (RBC, WBC)
Role of thymus
T cells mature
How do lymph valves open
An increase in hydrostatic pressure
What fibres trap microorganisms- immune system anatomy
Reticular fibres
In lymph
Trap then macrophages can destroy
Spleen and immune system
Red and white pulp
Red- remove aging RBC and blood borne pathogens
White- houses T and B cells
Innate and adaptive immune system
Name innate immune system cells
Basophils
Eosinophil
Mast cell
Adaptive immune system cells
Plasma cell
B cell
T cells- helper T, cytotoxic T, regulatory T
Cells considered both innate and adaptive
Neutrophil
Monocyte
Dendritic
Natural killer
Function basophils
Release histamines that cause inflammation (indirectly kill)
Eosinophil function
Kills parasites with oxidative burst
Mast cell function
Kills infected cells via cytolysis or apoptosis
Neutrophil function
Phagocytize bacteria or fungi
Monocyte function
Precursor to macrophage- macrophage can be fixed or wander, cause INFLAMMATION and perform PHAGOCYTOSIS
differentiate into macrophage
Dendritic cell function
Phagocytize bacteria and present antigens to T cells
In skin, respiratory, intestinalmucosa
Act as antigen presenting cell (APC)
Natural killer cell function
Kills cancer cells and virus infected cells
- do not target specific virus
Plasma cell and B cell function
Recognizes antigens and produces anitibodies
- plasma cell non specific antibodies
- B cells specific anitibodies
Helper T cell function
Secrete cytokines
Help activate B cells
CD4+ cells that bind MHC class II molecules in APCs
Cytotoxic T lymphocytes (CTL) function
License to kill- target specific abnormal cells (mug shot)
CD8+ cells that bind to MHC class I molecules
Regulator T cell (Treg) function
CD4+ cells that destroy cells that do not correctly recognize self cells
Name the stem cell type and the differentiation pathway to RBC, WBC, platelets
Pluripotent stem cells
- myeloid stem cell and lymphoid stem cell
Myeloid stem cell
- erythrocyte, platelet, mast cell, eosinophil, basophil, neutrophil (granular leukocytes), dendritic cell, monocyte
Lymphoid stem cell
- monocyte, T cell, B cell, plasma cell, natural killer cell (agranular leukocytes)
Function epithelial layer
Prevent entry- physical barrier, innate immune system
what is complements function
Acts as a bridge between the innate and adaptive immune system
- killing of microbes, opsonization of microbes, activate leukocytes
Uses circulating proteins
Function of cytokines
Inflammation
TNF- tumour necrosis factor
IL- interleukin
- immune signalling molecules recruited to site, aid, boost
Cytokine storm
Immune system goes into overdrive, start to target own tissues
Target audience for general infections
Weaker, not developed immune system individuals
- highest death in young and old
Target audience for Spanish flu
Strong immune system made it easier to kick into overdrive- cytokines storm
- 18-45 robust immune system target
Innate immunity- barrier types, cells in blood circulation, cells in tissue and lymph, response time
Physical barriers- skin, hair, secretions
Cells in blood circulation- granulocytes (basophils, neutrophils, eosinophils), mast cells, macrophages
Cells in tissue and lymph- monocytes, microglia, dendritic cell- all have soluble factors
Rapid response sec-min
Outer layer of skin describe
Epidermis
Dead and dying cells so bacteria comes off with layer
- layer has keratin- protein and keratinocytes- cells
What’s the problem with physical barriers and cystic fibrosis
No saline layer
Can’t move ex. Water, ions. So substance can’t be removed and gets trapped in tissue
Eye physical barrier mechanism
Substance contacts eye, lacrimal gland produces tears, remove substance
Or
Nasolacrimal duct connects eye to nose, can move substance this way and excrete via mucus
All barrier types and examples
Physical
- skin, lacrimal gland (eye), ciliary escalator, earwax, urine, vaginal secretions, peristalsis, defecation, vomit, diarrhea
Chemical
- sebum (forms protective film and lowers pH (3-5) of skin
- lysozymes destroy bacteria cell wall (in perspiration, tears, saliva, urine)
- gastric juice (1.2-3)
- vaginal secretions (3-5)
- oil, sweat
4 words for inflammation
Red, heat, pain, swollen,
What do histamines cause
Swelling, edema (fluid build up, lymph picks up), vasodilation
Function interleukins
Fever, migration of WBCs from blood vessels to site of infection
- positive feedback until problem cleared
- interleukins are a type of cytokine
Vascular reactions and phagocytosis- inflammatory response
- Chemicals- histamines, kinins, prostaglandins, leukotrienes, cytokines are released by damaged cells
- Blood clot forms
- Abscess starts to form
- Margination- phagocytes stick to endothelium
- Diapedesis- phagocytes squeeze between endothelial cells
- Phagocytosis of invading bacteria occurs
Where are monocytes found and where do they become macrophages
Monocytes circulate the blood stream
Macrophage when leave circulation
Types of macrophage receptors
LPS receptor- lipopolysaccaride ex. CD14 *
Toll-like receptor *
Fc receptor
Mannose receptor
Complement receptor *
IFN(gamma) receptor
Chemokine receptor (and cytokine) *
Phagocytosis steps and overall function
Engulf and break down bacteria/microbe
1. Chemotaxis and adherence of phagocyte to microbe- receptor (ex. Toll like)
2. Ingestion of microbe by phagocyte
3. Formation of phagosome- phagocytic vesicle
4. Fusion of phagosome with a lysosome- phagolysosome
5. Digestion of microbe by enzymes (hydrolytic) in phagolysosome
6. Formation of residual body containing indigestible material
7. Discharge residual bodies- waste material that can’t be broken down
Differences in invader vs human cells that are used for target recognition
dsRNA
- in replicating viruses
- recognition: ds-RNA activates kinase and TLR3 (toll like receptor 3)
- innate response: IFN(alpha or beta)
LPS (lipopolysaccaride)
- found in cell wall gram-negative bacteria
- recognition: LBP (lipo binding protein), CD14, TLR4
- innate response: macrophage activation
What do mast cells have
High affinity receptors for IgE
Pre-formed granules that contain inflammatory mediators (ex. Histamines, heparin)
Secrete cytokines, chemokines, leukotrienes
What do mast cell secretions cause
Cytokines- inflammation
Chemokines- infiltration by monocytes and neutrophils
Leukotrienes- muscle contraction and increase vascular permeability
Diapedesis steps
- Bacteria trigger local macrophages to release cytokines that act paracrine- neighbour
Mast cells release histamines- induce inflammation - Vasodilation and increased vascular permeability causes redness, heat, swelling, pain (erythema, edema)
- Neutrophils and monocytes are recruited, migrate through endothelial cell layer, release inflammatory mediators
