Intracellular immunization. Cloning and intracellular expression of a monoclonal antibody to the p21ras protein.

Following the demonstration that intracellular expression of antibodies ('intracellular immunization') may be utilized to engineer new traits in mammalian cells, we undertook experiments to perturb the function of p21ras proteins, by engineering the intracellular expression of the anti-p21ras antibody Y13-259. The variable regions of this antibody have been cloned and, after verifying their antigen binding activity, expressed in general purpose vectors for the intracellular expression of antibodies. The results confirmed that the cloned antibody has been efficiently expressed both in the secretory and the intracellular forms. Thus, intracellular immunization of mammalian cells against p21ras, or any other antigen for which a monoclonal antibody is available, can now be performed.