[razoroccam]

"I wonder if when the immune system is destroyed you lose all previous infection memory (mumps, measles, you name it) and have to build immunities all over again?"

Short answer: no.

Memory B and T cells are difficult to destroy. You'd have to get TBI (total body irradiation) to a level seen in Hiroshima to get to that state. Or be given chemo that will destroy the entire mucosal tract before it would kill memory cells. To give you an example, patients given high dose chemo for BMT (bone marrow transplant) still have intact memory B and T cells (as determined by responses to tetanus toxin, for example).

[neverdem]

Memory B and T cells are difficult to destroy. You'd have to get TBI (total body irradiation) to a level seen in Hiroshima to get to that state. Or be given chemo that will destroy the entire mucosal tract before it would kill memory cells. To give you an example, patients given high dose chemo for BMT (bone marrow transplant) still have intact memory B and T cells (as determined by responses to tetanus toxin, for example).

Interesting, do you have any links?

[Straight Vermonter]

The complete elimination of b cells is an experimental treatment for rheumatoid arthritis.

http://www.sciencenews.org/articles/20001104/fob5.asp