9 - Host defence overview Flashcards
What is the immune system for?
To defend against viruses, bacteria, fungi and parasites
What are surface defences?
Intrinsic epithelial barriers to infection.
Name 3 chemical barriers
Acids, Mucus, Anti-microbial proteins.
Name mucosal surface defences
Coughing, sneezing, mucus, cilia, rapid cell turnover
Pre-infection: ‘First line’
Avoidance, Smell, Taste, Mucus, Physical barriers, Surface environment
Early infection: ‘Second line’
Phagocytes, Opsonins, Lymphocytes, Interferons, Acute phase proteins, Toll-like receptors
Late infection: ‘Specific/acquired’
T cells
Antibody
Type I/III interferons are:
Alpha, beta, gamma
Function of type I/III interferons
Activates NK cells
Upregulates MHC, Mx proteins
Activates RNase L, PKR,
Induces anti-viral state
Type II interferons are:
IFNy
Function of type II interferons
Pro inflammatory
Th1 cytokine
“immune interferon”
Phagocytes are…
Cells that engulf invaders.
Leucocytes (white cells)
Antigen is destroyed in intracellular vesicles.
2 types of phagocyte are…
Macrophages and neutrophils
What is humeral immunity
Immunity via production of antibodies that travel in the plasma
Characteristics of an eradicable infectious disease
Simple (and cheap) to diagnose Genetically stable pathogen Accessible host species Eliminates persistent infection, or persistently infected host can’t transmit Safe and effective vaccine
The ideal vaccine
Completely safe Easy to administer Cheap Stable Active against all variants Life-long protection
Defences against bacteria
Surface defences (mechanical and chemical)
Antibody opsonisation
Complement (alternative pathway) causing lysis/opsonisation
Phagocytosis
Release of inflammatory mediators and acute phase proteins (also opsonins) etc.
Fever
Defences against viruses
Surface defences Interferons Inflammatory mediators and acute phase proteins/opsonins etc. NK cells Antibody, complement, ADCC T cells (mostly resolving infection)
