Unaltered immunoglobulin expression in hybridoma cells modified by targeting of the heavy chain locus with an integration vector.

Chimeric antibodies against the murine T-cell antigen Thy-1.2 were generated in amounts sufficient for in vivo studies by substituting the constant gene segments via homologous recombination in the hybridoma cell. We show that an integration vector targets the heavy chain locus at high frequency even in a non-isogenic situation. Using this vector type, for the first time expression rates were obtained that were identical to the parental hybridoma. The use of the gpt selection marker seems to be crucial for efficient expression, and may overcome a recently claimed drawback of vector integration. A chimeric antibody produced by gene targeting was characterized in vitro and in vivo.