The Amazing Macrophage

We have  been discussing the cells of the innate immune system in class.  Macrophages are often portrayed as fixed tissue cells which function as phagocytes and as APCs.  However, macrophages can do a lot of different things.  One of the most interesting recent finds is that macrophages can act as "nurse maids" for stem cells.  Actually the macrophages keep the stem cells in an immature state.   They do this by secreting prostaglandins. Check this out more here.

Here are some questions to ponder:

1 If macrophages guard stem cells where would you find them?  How do you propose they get to this location?

2 We have discussed several roles for prostaglandins.  We have also noted that prostaglandin inhibition is a major way to control inflammation.  Do you think prostaglandin inhibition factors (drugs) could alter the stem cell nurse/guard role of macrophages?  discuss.

3 What would be the role of preventing differentiation of stem cells?

4 Describe a way that you could test this special role of macrophages....i.e., what experimental system would you employ to show that this stem cell guarding function of macrophages is important to host immune function or host survival?





Due Dec 2




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Somatic Hypermutation and Chance and Design

Somatic hypermutation is an amazing process which increases the diversity of the antibody response and can also lead to an increase in antibody affinity over time. As we noted in lecture, the human body has the potential to make 10 billion different antibodies from just a few gene regions and somatic hypermutation helps increase this diversity.

Somatic hypermutation is a process which essentially involves specific but semi-random mutation events which are focused only on a small region of the antibody genes.  The small region just happens to be the binding site of antibodies for foreign antigens.

 Mutations at large in the genome are often deleterious, yet somatic hypermutation and a process of selection leads to positive benefit for the host.  Thus, from a design perspective we cannot say that all mutations or natural selection processes are neutral or bad or deleterious.



But from a design perspective, why use a mutation process to increase antibody diversity and affinity?

What are some of the advantages or dis-advantages involved in using a mutation system to increase immune function in this way?

Due Nov 20