[refurb]

I’m not a doctor, but I would say yes, you’d lose any acquired immunity since you kill off all the memory b-cells that store that information.

But you’d also gain the donor’s immunity, and if they’ve been vaccinated, the recipient would have that immunity as well.

[rnet85]

That is not correct. Trained B cells are predominantly stored in lymph nodes. You also don’t gain host immunity by marrow transfer.

[enchiridion]

So B cells are what responsible for learned immunity?