Memory B cells.

[CD19]

Hello,
I culture PBMCs (peripheral blood mononuclear cells) and I wonder if I have memory B cells in the culture. I know that there is almost no plasmacytes coz their per cent in full blood is very low. What about memory B cells?

If answer is "yes, there are memory B cells in your culture" then here goes another question. If I stimulate Th cells in culture only with anti-CD3 and thanks to their stimulation B cells are also stimulated so is it possible that memory B cells will response? Is anti-CD3 stimulation a secondary response for memory B cells? Anti-CD3 binds TCR on Th so is this sth new for them or normal situation coz they always catch sth through TCR? I think it is sth new coz they won't find sth so ideally similat to anti-CD3 in nature so even if I have memory B cells in culture they won't react on that.

[CD19]

I've been thinking much about the situation in my culture and I came to conclusion that there will be no secondary response and no IgG production. I still don't know if I am right. Even if there are memory cells in my culture they won't react on anti-CD3, coz they have never met in vivo such an antigen. There won't be also new memory B cells, coz no cell will present anti-CD3 to B cells and they won't bind it by BCR/CD19, coz anti-CD3 is specific for TCR in Th and Tc. So the only reaction of B cells is possible through stimulation with cytokines and surface antigens of Th, but it isn't enough (I think so) for differentiation to memory B cells, coz B cells haven't met the antigen (it is not specific to their surface antigens). So B cells as a fast response can turn into plasma cells and produce IgM (old mechanism, IgMs aren't so specific towards certain antigens), but I don't know how they could turn into plasma cells secreting IgG as a secondary response during culture. Can someone confirm?