Immunology 1 - Innate Immunity Flashcards
What are the key structures of a Prokaryotic cell?
- DNA (single and circular)
- Rigid/Complex Cell wall
- Enzymes and Ribosomes (free in cytoplasm)
- Plasma membrane
- Capsule
- Nucleoid
- Flagella (tail; for movement)
Where in the Prokaryotic cell is DNA found?
In the Nucleoid and Plasmids (Plasmid DNA = free in the cytoplasm)
What structure(s) does a Prokaryotic cell not have?
- Nucleus
- Mitochondria
- Golgi and Endoplasmic reticulum (ER)
What structure(s) does a Eukaryotic cell not have?
- Cell wall
Properties of a Nucleiod?
- Circular, Supercoiled, Double-stranded
- Associated with histone-like proteins
- Generally has only 1 chromosome
Properties of Plasmids?
- Small loops of extra DNA
- Not essential for survival
- Can be incorporated into the chromosome
How can Plasmids be incorporated into the chromosome?
A single DNA strand is tansferred b/wn cells by CONJUGATION (using ‘rolling circle’ replication’).
What are the 3 types of Active Transport in bacteria?
1) ABC transport (ATP binding cassette)
2) PMF driven transport
3) Group translocation
What is Peptidoglycan?
Highly cross-linked polymers made up of Carbohydrates and Amino acids
What does structural changes in Peptidoglycan allow for?
Allows for bacteria to be classified as GRAM +VE or GRAM -VE (Peptidoglycan layer = narrower in Gram -ve Cell wall)
What is a Pathogen (microbe)?
An organism that can cause disease
What are the 4 major groups of pathogens?
1) Viruses
2) Bacteria
3) Fungi
4) Parasites
Distinctive Pathogen
When 1 microbe = 1 disease
e.g: Plague, Typhoid
Pathogenic agents
Many microbes = 1 disease
e.g: Pneumonia, Septicemia (blood poisoning)
Pluripotential agents
1 microbe = many diseases
What is Commensal bacteria?
Bacteria we rely on for digestive survival
What is the role of the Immune System?
To protect from pathogens
What are two types of Immunity?
1) Innate immunity
2) Adaptive immunity
What are the two similar activities of the immune system?
1) Recognition (of invaders)
2) Response (Primary or Memory)
Components present before infection in Innate immunity include?..
- Skin
- Mouth/GI tract
- Lung/respiratory tract
- Phagocytic cells
- Soluble molecules
- Pattern recognition sequences
Examples of Pro-inflammatory Cytokines;
- Prostaglandins
- Leukotrienes
- Bradykinin
Examples of soluble components of Innate immunity;
- CAMs
- Chemokines e.g: Pro-inflammatory cytokines
- Defensins
What are the 4 families of CAMs?
1) Mucin-like
2) Selectins
3) Ig-Superfamily
4) Integrins
What is meant by Complement ?
A system of (30) soluble proteins
What is the main function of Complement activation ?
Recognises and destroys pathogens -based on recognition of pathogen-associated molecular patterns
Name 3 ways Complement activation destroys pathogens?
1) Phagocytosis
2) Lysis (of cells, bacteria and viruses) = disintegration of a cell by rupture of the cell wall or membrane
3) Inflammation
What is Opsonisation ?
Promotion of Phagocytosis (complement proteins cause microbes to bind therefore are easily digested by Phagocytes).
Name the 3 pathways for Complement activation in the complement system
1) Classical - Initiated by antibody binding to antigen
2) Alternative - DOES NOT INVOLVE ANTIBODIES. Involves direct contact b/wn antigens and complement factors
3) Lectin - (Proteins produced by the Liver when microbes are digested) (Lectin binds to carbohydrates on the surface of the microbe causing Complement activation).
What is the final product of Complement activation ?
The Membrane Attack Complex (MAC)
Name a major receptor of the Innate immune system ?
Toll-like receptors (TLRs) - non specifically triggers innate immune response
1) What are TLR’s ?
2) What do they form ?
3) Importance of TLR4 ?
4) How many types of TLR’s are there and what signalling pathway do they have ?
- They’re trans-membrane proteins with repeating sequence of AA’s
- They form Leucine-rich repeats (LRR’s) which form extracellular ligand (binding region of the TLR’s)
- They also have Intracellular TLR domain
- TLR4 = important in the recognition of bacterial LPS ( which is expressed in gram NEGATIVE bacteria)
- 11 types of TLR’s - all have Intracellular signalling pathways
What do cell surface TLR’s recognise ?
Extracellular ligands e.g: LPS
What do Intracellular TLR’s recognise ?
Intracellular ligands e.g: Viral DNA, Bacterial DNA and Nucleic acids
What do TLR 1,2,4 and 6 bind to?
Cell wall components
What does TLR 5 bind to?
Flagellin of bacteria
What does TLR 3 bind to?
Double stranded RNA
What is LPS ?
Extremely toxic Lipo-Poly-Saccharide that is expressed on the cell surface of gram negative bacteria. e.g: E-Coli
What are the major components of LPS ?
1) Lipid A (embedded in the membrane)
2) Core Polysaccharide
3) O-antigen polysaccharide
LPS’ are highly antigenic. TRUE or FALSE ?
TRUE -this varies between bacteria
The net negative charge over the cell surface of gram -ve bacteria allows it to evade an immune response. TRUE or FALSE ?
TRUE
Name 4 cellular components involved in the Innate immune system ?
1) NK (Natural killer) Cells
2) Macrophages
3) Neutrophil
4) Dendritic cells (similar to macrophages)
1 and 2 = extremely potent phagocytes
What are Granulocytes ?
Granular WBC’s = they possess a large number of cytoplasmic granules
Name the 3 types of granulocytes ?
1) Eosinophil (important in allergic reactions)
2) Basophil (least numerous WBC)
3) Neutrophil (involved in Innate immune system; acts as antigen presenting cells)
Neutrophils are the first to migrate from blood to tissue, upon infection of bacteria or fungi. TRUE or FALSE ?
TRUE
What is the Nonox/Oxidative defense and why is it important ?
Nonox defence = the production of ROS (reactive oxygen species) and RNS (reactive nitrogen species)
It is important as it is powerful for destroying ingested microbes
What type of bacteria does TLR2 recognise ?
What type of bacteria does TLR4 recognise ?
Gram +VE bacteria
Gram -VE bacteria
What is formed when an Oxygen molecule binds to additional electron ?
A Superoxide radical
Superoxide radical(s) form Peroxynitrite under which 3 enzymes ?
1) Phagocyte Oxidase
2) Superoxide dismustase
3) iNOS (inducible Nitric Oxide synthase)
Protons bind to Peroxynitrite to form…?
Peroxynitrous acid
Peroxynitrous acid dissociates into …?
Hydroxyl radical and Nitrogen di-oxide
Free radicals have been linked to aging in humans. TRUE or FALSE ?
TRUE
What are Interferon’s ?
Antiviral product
What do Mononuclear phagocytes consist of ?
Monocytes and Macrophages
monocytes differentiate into macrophages.
How many major types of Dendritic Cell’s (DC) are there ?
4
Common major function of DC’s ?
All types break down Antigen and present the fragments on MHC I or II molecules. All perform T Cell activation.
What does MHC stand for ?
Major Histocompatibilty Complex
What are the 4 types of DC’s ?
1) Langerhans DC
2) Interstitial
3) Myeloid
4) Plasmocytoid - stems from Plasmocytoid cells
First 3 = stem from Myeloid Stem Cells
