Effect of environmental pH on the efficiency of cellular hybridization

The hybridization of a human and mouse cell was strikingly pH-dependent, with a well defined optimum at (about) pH 7.6-8.0. The yield of hybrid cell colonies (1 per 500-2000 heterokaryocytes) was several hundred times greater than that obtained at pH 6.8-7.2. Although there was a significant effect on the efficiency of cell fusion, the critical time for the pH effect was in the first 4-8 days after fusion, presumably while viable hybrids were being formed from the multinucleated heterokaryocytes.