Immunity’s Early-Warning System. Scientific American, January 2005. For the foll

Question

Immunity’s Early-Warning System. Scientific American, January 2005.

For the following questions, please provide a general answer and a specific example – when possible.

How does the innate immune system recognize pathogens?

After recognizing pathogens, what is the response of the innate immune system? (ie. What action does it take?)

How does the innate immune response promote and adaptive immune response?

How can an immune response contribute to disease?

How can exposure to LPS lead to septic shock? What is a situation in which one would be exposed to LPS?

In what organism were Toll proteins first discovered?

What happens when a bacteria binds a TLR, for example LPS binding to TLR-4? How is the signal transmitted from the receptor to the cell, and in general what does it tell the cell to do?

Which TLR is a current target for improving the effectiveness of vaccines, ie. To act as an adjuvant?

Explanation / Answer

1. The innate immune response is non-specific. It recognizes specific patterns in foreign particles and destroys them. Many physical factors such as sweat or skin provide barriers to infection. Toll-like receptors recognize specific patterns present only in pathogens and initiate an immune response.

2. The innate immune system recognizes pathogens and activates phagocytic cells. Phagocytic cells endocytose these pathogens and digest them. They also present the pathogen sequences to B-cells so that specific antibodies can be produced against the pathogen.

3. Phagocytic cells digest the pathogen and present antigens on their surface to B-cells. B-cells recognize these antigens and produce specific antibodies. Phagocytes also secrete specific chemicals (Chemokines) that promote adaptive immune response.

4. i. Hyperactive immune response = Allergy = When immune system responds more than required for a given trigger.

ii. Autoimmune disorders = When immune system recognizes self-antigens and destroys them

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