Cell activation by CpG ODN leads to improved electrofusion in hybridoma production

Hybridoma formation is an indispensable step in the production of monoclonal antibodies. Obtaining highly efficient fusion of an antibody-producing cell to the myeloma cell to form the hybridoma is an important step in this process. The electrofusion method is superior to chemical fusion methods such as the polyethylene glycol (PEG) method due to its high fusion efficiency. However, this method requires cell activation prior to electrofusion, a process that is time-consuming and tends to cause cell death. In this study, we achieved much higher fusion efficiency by stimulating B cells with CpG oligodeoxynucleotide (CpG ODN) over shorter periods. Splenocytes were isolated from immunized mice and cultured in the presence of a CpG ODN for 1 or 2 days. This CpG ODN stimulation evokes about one order of magnitude higher fusion efficiency than other stimulators. CpG ODN stimulation not only increases the fusion efficiency but also the number of antibody-producing cells. This leads to a substantial increase in the number of positive clones obtained. This highly efficient fusion method was used to produce a functional antibody against Gaussia luciferase. This method was found to produce greater numbers of hybridomas and to enable direct screening for antibodies with functional characteristics such as inhibition of the luminescence activity of an antigen. We were able to establish a functional antibody against Gaussia luciferase after a single fusion experiment using our electrofusion method.