CHIMERIZATION OF ANTITUMOR ANTIBODIES VIA HOMOLOGOUS RECOMBINATION CONVERSION VECTORS

Homologous recombination vectors were designed to convert murine hybri doma cell lines expressing IgG3, IgG1, or IgG2a heavy chains into chim eric human IgG1 producers. These conversion vectors included homology both upstream and downstream of the target sequences and consistently resulted in a higher frequency of successful gene targeting than an in sertion vector bearing a single region of homology. A human kappa ligh t chain conversion vector was also constructed and used to complete ch imerization of the anticarcinoma hybridoma cell line BR96. The resulti ng cell line expressed antigen-specific chimeric antibody at comparabl e levels to those found in the murine parental cell line. Southern blo ts confirm that recombination occurred within the upstream and downstr eam regions of homology for both vectors, resulting in the loss of mur ine constant region sequences.