Immunology Flashcards
What is the difference between intracellular and extracellular bacteria?
- Intracellular can enter and survive inside the host organism
- Extracellular cannot survive inside the host once the phagocyte is ingested
What is the definition of virulence?
The ability to infect the host and cause disease
What are issues with the evolution of HIV?
The antigenic drift is very rapid and therefore outpaces the development of the immune response which causes disease
How does the flu spread so rapidly?
The recombination of the RNA sequence which further mutates to cause more epidemics
In 1918, what major thing did the Spanish flu do?
Crossed the species barrier
What does altering the surface proteins on a pathogen do?
It means they can avoid host immune response
What is the difference between a primary and a secondary response?
- Primary response takes 7-10 days and is not very strong
- Secondary response takes 4-6 days and is very powerful, memory improves here due to memory cells
What immune response do we depend on in the first few hours/ days?
Innate immunity
What can the immune system check to distinguish between self and non-self at a molecular level?
- Bacterial cell wall
- Protein and peptide structures
- Yeast carbohydrates
- Pathogenic DNA
- Viral antigens on host cells
What tissue uses only it’s own immune response?
The brain, through the blood brain barrier
Why must the immune system give the right amount of response?
Or else it will not clear it or it may damage the host
What are the two types of immune response?
Innate and adaptive
What are mucus layers?
- On epithelial surfaces
-Secreted from mucins and glycoproteins - Slippery so pathogens can’t attach
- Have cilia
What are defensins?
- Hydrophobic domains
- 12-50 aa in length
- positive charge
- in all plants and animals
They kill and inactivate pathogens using an uncertain non-specific mechanism
Why are PAMPs useful?
They look for something different in the body which is recognised by PRRs in the blood
Name 3 classes of PAMPs
- fMet attracts neutrophils
- peptidogylcans from cell walls
- bacterial flagellae
- lipopolysaccharides (LPS)
- mannans, glucans and chitin from fungi
- motifs from bacterial or viral DNA
What do toll receptors do?
Pathogenic fungi bind to repeating motifs which sends signal to nucleus which expresses antifungal defensins.
Basically nucleus feels the signal and inflammatory response is triggered.
Where are toll like receptors found?
- epithelial cells
- macrophages
- dendritic cells
- neutrophils
How old are TLRs and PAMPs believed to be?
1576 million years old
What is evasion?
LPS is replaced with LOS so it is not recognised by immune system and evades it, it mimics a body cell
What are the 3 types of phagocyte?
- Macrophage
- Neutrophil
- Eosinophil
What two types of cell are granulocytes?
Neutrophils and eosinophils
What are neutrophils?
Most common phagocyte which are rapidly recruited but short lived, they have a bright pink nucleus
What are macrophages?
They recognise and remove dead and damaged cells, they are long lived
What are eosinophils?
They destroy parasites and modulate allergic inflammatory responses, they work together. They also stain with eosin stain.
What happens during a respiratory burst?
Increase in oxygen consumption
What happens in a killing frenzy?
- Loads of stuff dies
- Stuff inside macrophages die
- Inflammation aids the frenzy
- Can cause septic shock
What do interferons do?
- inferfere with vial infection
- activate other mechanisms
- promote apoptosis
- fight cancers
How do NK cells work?
Apoptosis is triggered and the bodies left behind are engulfed by phagocytes
What does the R number represent?
Number of secondary cases
Where do lymphocytes develop and migrate to?
Develop in the bone marrow and migrate to peripheral / secondary lymphoid organs
What activates the adaptive immune response?
Dendritic cells activated by binding of pathogens to TLRs
Where do T cells develop?
Develop from thymus tissue from thymocytes
What do T cells do?
They recognise non self antigens and cause mitosis and clonal expansion of specific T cells. Causes swelling in lymph glands.
What do cytotoxic T cells do?
Recognise antigens and activate caspases from signals
Where do B cells develop?
Bone marrow
What do B cells do?
- Antibody specific secretion
- Recognise antigens as soluble proteins
- Clonal expansion
Name the 5 classes of immunoglobulin (Ig)? How are they distinguished?
IgM
IgD
IgG
IgA
IgE
They are distinguishable by their H chains
How many polypeptide chains do antigens have?
4
What is affinity maturation?
Antibodies made by B cells in lymph nodes improve affinity and become more specific.
