Persistence of the Fc cytophilic antibody receptor in macrophage hybrid cells.

Hybrid cell clones were obtained from mouse macrophase/Ehrlich ascites cell fusions which showed the 'Fc' cytophilic antibody receptor site, phagocytosis and motility typical of macrophages. With continued growth of the clones for 11 weeks, the receptor became undetectable but could be unmasked by dilute trypsin treatment; subsequent remasking of the receptor could be prevented with cycloheximide treatment of the hybrid cells. These hybrids produced cystic anaplastic tumours in neonatal irradiated mice. Chinese hamster/mouse interspecific macrophage hybrid cells did not show macrophage markers. This was probably due to rapid loss of macrophage chromosomes from the hybrid cells.