Expression of recombinant idiotype in SFV-transduced DC.

Lymphoma-derived immunoglobulin genes were inserted with an attached hexahistidine tag into the SFV vector plasmid pSFV1. In vitro transcripts were synthesized from idiotype SFV vector plasmids, and the helper plasmid pSFVhelper1. BHK-21 packaging cells were electroporated with a mixture of helper and idiotype vector transcripts. Twenty-four hours later, infectious BHK-21 supernatants were harvested and used for transduction of terminally differentiated DC at 1:1, 1:10, and 1:100 dilutions. Twenty-four hours after transduction, DC were lysed and analyzed by Western blot with an antihistidine antibody. Bound antibody was detected by chemiluminescence. rec Fab, recombinant Fab fragment loaded as control; SFV/Fd, SFV/IgL, transduction with SFV vectors encoding the heavy- or light-chain idiotype of the respective patient's lymphoma; SM, 10- to 250-kd molecular weight marker.