Dear Quyen,

are you going to perform antigen-specific Elispot by coating the antigen? Then, you could just coat anti-Ig for your positive control. Or are you looking for an unspecific B cell stimulus to induce antibody secretion in your positive control. Here, LPS might do the job. I also attached a paper describing two different ways of doing an B cell Elispot.

Good luck,

Michael

http://www.jimmunol.org/cgi/doi/10.4049/jimmunol.0900407

I agree with Michael and would add that if you want to evaluate the specific memory B cells, You can also use the memory B cell specific for  the tetanus toxin because almost everyone is vaccinated and should have enough of these cells

Good point Bourema,

but only valid for human samples. Quyen is working with murine samples. I would be suprised to see tetanus responses in these animals.

Best,

Michael