Question

For bacteria from your skin to cause an overt infection, it has to evade several layers of the immune response. The innate immune system clears most infections before they reach the level necessary for adaptive immunity.

1. Discuss the cells and effector molecules involved, as well as the kinetics of this innate response.

2. When the innate immune system fails to completely clear an infection, the adaptive immune system is activated. How and where does the adaptive immune system get activated? What major cell types and molecules are involved?

3. How does the innate immune response facilitate the adaptive immune response?

4. Upon activation, cells of the adaptive immune system can be pushed towards multiple fates. How are they directed towards these fates and by which cells? How do adaptive immune cells know where to go to fight a bacterial insult?

Answer 1

1.

Innate immune system is the first line of defense and the response in innate immune system is nonspecific. The innate immune cells involved in the given scenario are macrophages, dendritic cells and the natural killer cell.

PAMPS and TLRs are the effector molecules whose interaction helps in induction of the production of cytokines.

2.

Adaptive immune system is activated by antigen presenting cells of the innate immune system. APCs like DC and macrophages process the pathogen and present it to their surface for the activation of Th cells. A cascade of adaptive immune system begins as B cells and cytotoxic T cells also get activated with the help of Th cells. Interleukins and antibodies are the major molecules involved in the adaptive immune system.