Does the fact that sIgA does not activate complement make it less effective in preventing infection than IgG?

Reading Review Questions – Chapter 4
The Power of Bacteria

2. Does the fact that sIgA does not activate complement make it less effective in preventing infection than IgG?

Hint: Consider its location and function.

4. Why is a Th1 or Th2 cell needed to mediate APC-initiated antibody production? Why do the B cells not bind directly to the APCs?

6. There are many interactions between the innate and adaptive defense systems. List as many of them as you can and explain how they work. Why are these interactions important? Are all of them beneficial?

8. Why is the level of specific IgM antibodies of diagnostic significance?

10. Listeria monocytogenes is a foodborne, Gram-positive bacterium that causes infections (listeriosis) in individuals with compromised immune systems. Listeria is predominantly an intracellular pathogen. After phagocytosis by intestinal macrophages, Listeria escapes the phagosome and replicates in the cytosol before spreading to other neighboring cells through a special invasion process that allows it to remain intracellular while spreading from cell to cell.

a. What advantage is there for Listeria to invade and spread intracellularly?

b. What immune response is primarily responsible fore controlling Listeria infection in healthy but unimmunized individuals?

c. What immune response is primarily responsible for controlling Listeria infection in healthy but immunized individuals or those having prior exposure?

d. How are Listeria antigens presented to immune cells?

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