CMB2004/L08 Immunity Against Infection I Flashcards
What bacteria causes food-poisoning?
Salmonella
Which bacteria causes tonsillitis?
Streptococci
What factors do the different effector mechanisms needed to fight infection dependent on? (3)
Type of pathogen
Localisation
Challenge
Stage of infection
Give the 4 host defence mechanisms in order of action/
Anatomic barriers
Complement/antimicrobial proteins
Innate immune cells
Adaptive immunity
Give 3 cells involved in the innate defence mechanism.
Complement
Phagocytes
NK cells
Antimicrobial peptides
What is the role of T(H)1 cells?
Active against intracellular pathogens
Activate macrophages and stimulate cytotoxic T cells (CD8+ cell)
What is the role of T(H)2 cells?
Active against extracellular pathogens
Support antibody production, particularly to IgE
Activate eosinophils, basophils and mast cells
What is the role of T(H)17 cells?
Active against extracellular bacteria and fungi
Attract inflammatory cells e.g., neutrophils
Give an example of a Gram positive bacteria.
Staphylococcus aureaus
Streptococcus spp.
Give an example of a Gram negative bacteria.
Campylobacter
Salmonella
Shigella
Haemophilus
Neisseria
Describe the cell wall of Gram positive bacteria.
Lipid bilayer plasma membrane with integral proteins
Lipoteichoic acids traversing wall and anchored in membrane
Describe the cell wall of Gram negative bacteria.
Lipid bilayer plasma membrane with integral proteins
How can components of bacterial cell walls induce innate responses?
Binding to Toll-like receptors (TLR) on macrophages
Where are distinct molecular patterns that are recognised by receptors on pathogens?
Plasma membrane
Endocytic vesicles
Where are NOD-like receptors found?
Cytoplasm
What do Toll-like receptors bind?
Pathogen-associated molecular patterns (PAMPs)
What does binding of PAMPs to TLRs trigger? (2)
Inflammation
Dendritic cell maturation
Influence differentiation of T cells
Activate B cells
What do TLRs on the endosome membrane recognise?
Microbial components exposed after microbe has been broken down
How can the bacterial capsule be overcome by the body’s defences?
Opsonisation by antibody/complement
Give 3 roles of antibodies in bacterial infection.
Opsonisation
Complement activation
Bind to and neutralise toxins
Bind to surface structures to prevent mucosal adherence
How can Gram negative bacteria be killed?
By complement lysis
Which cells are central to the T(H)1 response?
Macrophages
Give an example of a bacterium which can survive within phagocytes.
Mycobacterium tuberculosis
Inhibit lysosome/phagosome fusion
Describe the body’s response to:
a) tuberculoid leprosy
b) lepromatous leprosy.
a) Strong T(H)1 response, few live bacteria, slow progression, granuloma formation
b) Strong T(H)2 and antibody response, lots bacteria in macrophages, disseminated infection, fatal
Describe how a granuloma is formed.
Macrophages engulf foreign material but cannot eliminate it
Become activated
Become giant cells and fuse together
More inflammation with lymphocytes
Describe tuberculoid leprosy.
Low levels of bacteria
Low infectivity
Granulomas and local inflammation
Peripheral nerve damage
Normal serum immunoglobulin levels
Normal T cell responsiveness
Describe lepromatous leprosy.
Florid growth in macrophages
High infectivity
Disseminated infection
Bone, cartilage, and diffuse nerve damage
Hypergammaglobulinemia
Low or absent T cell responsiveness
In which form of leprosy are monokines produced?
Granulomatous
