Immunity to Infection: Sequence and Timing

Question 1

What are the steps go the immune response to infection?

Answer 1

Microbial detection
innate immune response
Adaptive immune response
Memory response

Question 2

What are the main features of the innate immune system?

Answer 2

Physical barriers
Humoral: Complement, Lectins, Pentraxins, Antimicrobial peptides
Cellular: Neutrophils, Macrophages, Dendritic cells and NK cells

Question 3

What are lectins?

Answer 3

Proteins that bind sugars

Question 4

What does humoral mean?

Answer 4

Plasma components

Question 5

What are the main features of the adaptive immune system?

Answer 5

Humoral: Antibodies
Cellular: Cytotoxic T-cells, T-helper cells, T-reg cells, B-lymphocytes and plasma cells

Question 6

What are the main differences between innate and adaptive?

Answer 6

Timing
Cell types
Receptors and ligands
Cytokines and chemokines
Molecular effector machineries

Question 7

How does an immune response to infection start?

Answer 7

Tissue damage

Detection of pathogens

Question 8

Who are the first responders?

Answer 8

Neutrophils and macrophages

Question 9

What initially happens?

Answer 9

Neutrophils response first (short-lived 6hrs)
Macrophages follow
Naive cells become activates upon interaction with microbes
Phagocytes control infection and limit/repair tissue damage

Question 10

Why would uncontrolled activity be bad?

Answer 10

Granulomas
Excessive inflammation and inappropriate adaptive immunity
Tissue damage

Question 11

What are lnterleukins?

Answer 11

Small molecules used from communication between leukocytes

Question 12

What is the general sequence of molecular and cellular events?

Answer 12

Microbial ligands
Naive host cells
Cytokines and chemokines
Activated host cells

Question 13

What is macrophage activation?

Answer 13

Expression of many new genes

induced by microbes and cytokines

Question 14

What is enhanced in activated macrophages?

Answer 14

Phagocytosis and migration
Cytokine/Chemokine production
Expression of cell surface molecules 
Anti-microbial activity
Antigen presentation and T-cell activation

Question 15

Are phagocyte responses pathogen specific?

Answer 15

Yes

Question 16

What are interferons?

Answer 16

Special cytokines

Direct antiviral responses

Question 17

How do dendritic cells and macrophages activate T-cells?

Answer 17

Present antigens in combination with MHC-I or MHC-II
Cytokines produced, produce suitable milieu for T-cell activation
T-cells then provide cytokines that activate phagocytes

Question 18

How do T-cells help B-cells produce antibodies?

Answer 18

T cell activation by MHC and foreign peptide recognition

B cell activation for antibody production against antigen

Question 19

What does phagocyte activation allow for?

Answer 19

Enhanced killing of pathogens

Inflammation

Question 20

What does direct killing of infected cells do?

Answer 20

Removes replicative niches

Question 21

What does B cell activation do?

Answer 21

Antibody production and affinity maturation

Question 22

What does the innate lymphoid cells do?

Answer 22

Early responders

MHC independent reaction

Question 23

Where are memory cell stored?

Answer 23

Mainly in the spleen

Question 24

Summarise the sequence of the immune response

Answer 24

Sequential change from naive to activated
Driven by gene expression change driven by cytokines
Differentiation of precursor cells into specific lineages of cells