Immunology Flashcards
Revision of immunology from principles
What is the immune response divided up into?
- Innate/ natural: natural barriers, soluble components and cellular components
- Acquired/ adaptive: humoral (B cells) and cell-mediated (T cells)
What are the main barriers to infection?
- Skin
- Mucous
- Commensal bacteria
How does the skin provide a barrier to infection?
- physical barrier= highly keratinised, multi-layered
- physiological factors= low pH, low oxygen
- sebaceous glands= hydrophobic oils, lysosomes, ammonia, antimicrobial peptides
How does mucous provide a barrier to infection?
lines resp, GI and urogenital surfaces
- physical barrier
- secretory IgAP: prevents bacteria and viruses penetrating epithelial cells
- enzymes: lysosomes, defensives and antimicrobial peptised
- cilia
How does commensal bacteria provide a barrier to infection?
- symbiotic relationship
- makes vitamins K and B12
- makes bactericides
- low pH
- compete for nutrients
- make anti-microbial fatty acids
What are the main components of the innate immune system?
- leukocytes:phagocytic white blood cells, macrophage, neutrophil, natural killer cells
- complement: destroys cells
- inflammatory response: increase temperature, capillary permeability and attract macrophages
What do natural killer cells do?
release perforin, forms pores so fluid moves in and out, cell lysis and apoptosis
What does the complement system do?
- attacks bacteria a fungus
- forms a membrane attack complex
- perforates cells to cause apoptosis
What does the inflammatory response do?
- releases histamines and prostaglandins
- capillaries dilate and become leaky (macrophages, RBCs, platelets and clotting factors)
- increased temperature (decreased bacterial growth, phagocytosis and increased repair)
What is the innate immune system?
present continuously and from birth
What is the adaptive immune system?
induced by the presence of foreign material and is specific
What are the main specific cells of the innate immune system?
- macrophages
- dendritic cells
- natural killer cells
- mast cells
What are the features of macrophages?
develop from monocytes, large pale pink cytoplasm, kidney bean nucleus
What do dendritic cells do?
present in large numbers in tissues, APCs
What do natural killer cells do?
granular, kill infected cells and cancer cells, kill antibody bound cells and pathogens
What do mast cells look like and do?
fried egg appliance, granular, protect mucosal surfaces
What are PAMPs?
pathogen associated molecular pattern which are on the surface of pathogens
What are PRRs?
pattern recognition receptors that are on the surface of cells and intracellular to bind to and detect PAMPs
What is phagocytosis facilitated by?
opsonisation so macrophages can engulf pathogens
What are the main steps of phagocytosis?
- macrophages express PRRs
- PRRs bind to PAMPs
- phagocytic cup engulfs target to form phagosome
- fusion with lysosomes to form phagolysosome
- debris released into extracellular fluid
- pathogen-derived peptides expressed on MHC-II
- pro-inflammatory mediators released eg TNFalpha
What is opsonisation?
coating of pathogens by opsonins to enhance phagocytosis
What do virally-produced interferons activate?
immune cells
signals nearby infected cells to undergo apoptosis
signals nearby uninfected cells to decrease protein synthesis and destroy RNA
What cells to natural killers target?
cells with less MHC-I so virally infected and cancer cells
What happens when mast cells degranulate?
- release pro-inflammatory mediators
- increased acute inflammation
What is macrophage activation enhanced by?
IFNgamma (made by NKC)
increased MHC-II expression
What is neutrophil trans-endothelial migration?
gets neutrophils to the tissues through the blood and is triggered by pro-inflammatory mediators