Suppression of Immunoglobulin Synthesis by Cellular Hybridization

WHEN two cells which show differentiated characteristics are fused, the hybrids generally do not show these characteristics. Ephrussi et al.¹ have interpreted such trans dominant loss to show that the cells contain a diffusible repressor and this idea is supported by the finding that some mouse/human hybrids can spontaneously redifferentiate when the C10 human chromosome is lost². We now report another example of redifferentiation in hybrid cells; when IT mouse fibroblasts are fused with MPC 11 mouse myeloma cells which produce immunoglobulin, the hybrids neither produce nor excrete detectable amounts of immunoglobulin.