Increased prostaglandin E release and tumor cytostasis by resident Kupffer cells during Listeria monocytogenes infection.

Liver macrophages isolated from Listeria monocytogenes-infected mice were studied for their functional capacities in vitro. Spontaneous release of prostaglandin E and tumor cytostatic activity by liver macrophages of infected mice were markedly enhanced when compared to controls. Irradiated mice showing no increase in the number of their liver macrophages after Listeria monocytogenes infection, in contrast to solely infected mice, nevertheless demonstrated comparable activities. Our data suggest that radioresistant liver macrophages, most probably resident Kupffer cells, can be activated during in vivo infection to express enhanced effector functions.