Examine Figure 43.20 and focus on the acquired immune system events following first exposure to an antigen. This was the case for the sailors, coal miners, and everyone else infected in 1918.

a. How are the innate and the acquired immune systems linked? How does one system inform the other of an invasion by a foreign particle?

b. In the acquired immune response, which cells undergo clonal selection once their receptors have joined with one of the antigens?

c. Why is clonal selection a key event in whether or not the acquired immune response is successful?

d. B plasma cells are effector B cells that fight off the infection differently than cytotoxic T cells do. Explain.

e. Although not a factor in disease caused by influenza A, what would be the effect on the acquired immune response if the helper T cells were removed from the system? (The virus causing the current AIDS pandemic targets such T cells.)