Lymphokine-Activated Killer Cells Lyse Listeria-Infected Hepatocytes and Produce Elevated Quantities of Interferon-γ

The bulk of Listeria monocytogenes injected intravenously into mice is taken up in the liver, where hepatocytes serve as the principal site of intracellular replication. NK cells have been implicated in host defenses to a variety of intracellular pathogens. To explore the role of NK cells in resistance to listerial infections of the liver, lymphokine-activated natural killer (LAK) cells were cocultured with Listeria-infected hepatocytes. The aspartate aminotransferase activity in the medium (evidence of cytotoxicity and hepatocyte damage) was elevated significantly in these cultures. Conversely, the viability of intracellular Listeria organisms was reduced. Increased quantities of interferon-γ (IFN-γ) were also detected. IFN-γ production by LAK cells was modulated by interleukin (IL)-2 and IL-12. These findings suggest that the response of LAK cells to infected hepatocytes may play a critical role in host defenses to Listeria organisms taken up in the liver.