5. Response to Bacterial Infection Flashcards
What innate response is triggered when a bacteria breeches a barrier?
Complement activation
Phagocytosis
Inflammatory response
What is the classical complement pathway activated by?
Antibody recognition
What is the alternative pathway activated by?
Peptidoglycans in the bacterial cell wall
What is the lectin pathway activated by?
Bacteria with mannose on the surface
What bacteria is particularly susceptibly by MAC formation?
Neisseria
What receptors initiate phagocytosis?
Mannose receptors
Scavenger receptors
What factors increase phagocytosis?
C3b
Cytokines released by NK and Th
What is the function of Toll-like receptors?
Cause production of TNF, IL1,6 that mediate inflammation and direct adaptive response
What type of Th is important for extracellular bacteria?
Th17
What is the role of T cells?
Produce cytokines which increase inflammation and phagocytosis
Help B cells produce antibodies
What is the role of antibodies?
Neutralise
Activate complement
Promote opsonisation
What TLR reacts to gram + bacteria?
1,2,6
What TLR reacts to gram - bacteria?
4
Which TLRs react to viruses?
3,7,9
What instructs the differentiation of Th17 cells?
IL-23
What cytokines do Th17 cells produce?
IL-17, 22
TGF-b
What diseases are due to a lack of Th17 cells?
Psoriasis
MS
Crohn’s
What are the functions of Th17 cells?
Recruit neutrophils
Release antimicrobial peptides
Increase barrier integrity
What is the T dependent B cell response?
B cells are activated by Th in response to a protein antigen
What do T cytokines cause B cells to do?
Proliferate
Class switching
Differentiation
What does the T dependent pathway result in?
Memory B cells
Any type of antibody is produced
What is the T independent pathway activated by?
Polysaccharide antigen
What does the T independent pathway result in?
Low affinity, short lived plasma cells
IgM production
Why does hyposplenism result in susceptibility to encapsulated bacteria?
Deficiency of T cell independent antibodies
How is hyposplenism managed?
Prophylactic antibiotics
Immunisation
Annual measurement of antibody titres
What Th cell is important in helminth infections?
Th2
What is Th2 activated by?
IL-10
What does Th2 produce to stimulate IgE?
IL-4
What effect does IL-4 and IL-3 have?
Stimulate mucous production and intestinal paralysis
