Genetic engineering of anticolorectal carcinoma Fv molecule in myeloma cells.

The anti-TAG72 Fv molecule composed of a heterodimer of both heavy- and light-chain variable domains was produced by the construction of the expression vector mpSV2neo-EP1-Fv72.3. This vector contained the neo gene as a selection marker, the murine immunoglobulin heavy chain promoter (P1), enhancer (E), the SV40 polyadenylation signal region, and the murine cDNA fragments of VH and VL regions amplified and cloned directly from the B72.3 hybridoma RNA by the polymerase chain reaction technique. Termination codons were introduced into the 3' end of both VH and VL regions. The expression vector was transfected into the SP2/0 cell line. The Fv72.3 molecules were purified by the rabbit anti-B72.3 idiotype antibody affinity column, and retained the binding reactivity for the TAG72 antigen. The small size of Fv72.3 molecule (25 kD) makes it attractive for structural studies and immunodetection of cancers.