MAMMALIAN-CELL EXPRESSION OF SINGLE-CHAIN FV (SFV) ANTIBODY PROTEINS AND THEIR C-TERMINAL FUSIONS WITH INTERLEUKIN-2 AND OTHER EFFECTOR DOMAINS

The production of several single-chain Fv (sFv) antibody proteins was examined by three modes of mammalian cell expression. Our primary model was the 741F8 anti-c-erbB-2 sFv, assembled as either the V-H-V-L or V-L-V-H, and expressed alone, with C-terminal cysteine for dimerization, or as fusion proteins with carboxyl-terminal effector domains, including interleukin-2, the B domain of staphylococcal protein A, the S-peptide of ribonuclease S, or hexa-histidine metal chelate peptide. Constructs were expressed and secreted transiently in 293 cells and stably in CHO or Sp2/0 cell lines, the latter yielding up to 10 mg per liter. Single-chain constructs of MOPC 315 myeloma and 26-10 monoclonal antibodies were also expressed, as were hybrids comprising unrelated V-H and V-L regions. Our results suggest that mammalian expression is a practical and valuable complement to the bacterial expression of single-chain antibodies.