Production of hybrid hybridomas based on HAT super(s)-neomycin super(r) double mutants

A detailed procedure is described for the preparation of hybrid hybridomas, that produce bispecific antibodies. This is achieved by fusing two hybridoma cell lines that are phenotypically distinct (HAT super(s)/neo super(r) and HAT super(r)/neo super(s)) and thereby allow for the selection of the appropriate hybrid cells. HAT super(s) mutants were obtained from one of the two fusion partners by 8-azaguanine treatment; these mutant phenotypes were found in an unexpected high frequency. This method was very effective in the production of hybrid hybridomas, so-called quadromas.