Efficiently transfectable T- or B-cell lines known ?

[Jan Michel]

Hello,
I have problems with transfecting Jurkat or Raji cells by electroporation 
with efficiencies higher than about 7 %. Does anybody know a human T- or 
B-cell line that can be better transfected ?
I'm using the Biorad pulser at 200 V / 960 µF.

Thanks
                     Jan