Local proliferation and extrahepatic recruitment of liver macrophages (Kupffer cells) in partial-body irradiated rats.

The relative significance of local proliferation and extrahepatic recruitment of Kupffer cells was investigated by partial-body irradiation before the induction of macrophage hyperplasia by zymosan. There was no difference in growth of the Kupffer cells population between nonirradiated rats and rats irradiated with the liver shielded, whereas irradiation of the liver with the rest of the body (bone marrow) shielded resulted in strong inhibition of growth (-61%). Splenectomy combined with bone marrow irradiation inhibited growth to a lesser extent as compared to liver irradiation (-38%). Monocyte and other leukocyte numbers were strongly reduced in peripheral blood and their accumulation in the liver was completely prevented by bone marrow irradiation. Our results demonstrate that local proliferation of resident Kupffer cells represents the predominant source for their increased number during hyperplasia.