Lecture 15 - Integrated Dynamics of Innate and Adaptive Immunity

Answer 1

Immune response starts as an Antigen (Ag)-independent response. i.e. innate.

With time the immune response becomes more focused:
Firstly on the type of pathogen – i.e. bacteria/fungi/worm.
Then on the specific pathogen – Ag-dependent responses develop.
This allows activation of the most effective responses.

At all time points during the response innate immunity is involved.

At later time points adaptive immunity can become active.

Answer 2

STAGE 1: Barrier Breach
STAGE 2: Activation of Innate Immunity
STAGE 3: Lymphatic Spread
STAGE 4: Adaptive Immune Response

Question 3

STAGE 1: Barrier Breach

Answer 3

Not as straight forward as it sounds.
The invader must be able to adhere, penetrate or colonize the tissue it has invaded.
It must be able to replicate in the environment it has found itself.

MAMPs and DAMPs released

Question 4

STAGE 2: Activation of Innate Immunity

Answer 4

Innate immune cells are activated:
Tissue resident macrophages.
Tissue resident Dendritic cells.
Epithelial cells.

All produce Cytokines and Chemokines

ILCs and TCRγδ+ T cells are activated

Cytokines and Chemokines

Endothelial Cells are Activated.
Expression of integrins and other molecules which allow recruitment of circulating innate immune cells.

Endothelium becomes leaky
Allows entry of serum proteins, for example complement into the tissue.

KEY POINTS:

Activation time is very rapid, occurring within minutes of the infection.

Duration: This innate immune response is sustained for several days.

Largely non-specific in nature.
Although cytokines made by ILCs (for example) will start to tailor the response.

A lot of pathogens can be controlled at this stage

Question 5

STAGE 3: Lymphatic Spread

Answer 5

Adaptive immunity is triggered when the infection eludes the local innate responses OR a threshold of antigen is met.

Question 6

STAGE 4: Adaptive Immune Response

Answer 6

Ag-specific T cells and antibodies entre the site of infection.
Due to Ag-specificity these responses are more powerful than those in the early stages as they allow precise targeting of the pathogen.

Question 7

ILC1

Answer 7

Help co-ordinate activation of…
Th1 cells
IgG1 and IgG2

Potentiates the Activation of…
Macrophages and monocytes

Question 8

ILC2

Answer 8

Help co-ordinate activation of…
Th2 cells
IgE

Potentiates the Activation of…
Eosinophils, Mast Cells, and Macrophages

Question 9

ILC3

Answer 9

Help co-ordinate activation of…
Th17 cells
opsonizing IgG

Potentiates the Activation of…
Neutophils