Somatic cell hybrid selection with a transfectable dominant marker

A recombinant plasmid vector, pSV2-neo, coding for resistance to neomycin and the related antibiotic G-418, was transfected into the mouse myeloma line X63-Ag8.653 by a modification of the protoplast fusion technique. The time interval required to obtain 10(6) G-418 resistant cells was 20 days and the efficiency was 10(-4)-10(-5), which represents a significant advantage over classical methods of selecting mutant cells bearing a dominant selection marker. To investigate the efficiency of this marker in somatic cell hybrid selection, these cells were fused to the human myeloma line U-266 and the hybrids were selected either in HAT + G-418 or HAT + ouabain. The pSV2-neo vector was as efficient as ouabain as a dominant marker with respect to the number of viable hybrid colonies selected and their levels of immunoglobulin secretion. The reciprocal experiment was also performed: HAT-sensitive, mutant U-266 cells were transfected with pSV2-neo, clones selected in G-418 and fused with X63-Ag8.653 cells, and hybrids selected in ouabain plus G-418, yielding HAT-sensitive hybrid "heteromyelomas" that were effective fusion partners with human B lymphocytes.