Exudation of proliferative macrophages in local inflammation in the peritoneum.

Thioglycollate (TG)-elicited peritoneal macrophages (m phi s) were highly proliferative and formed m phi colonies in vitro in the presence of m phi colony-stimulating factor (M-CSF), while resident peritoneal m phi s did not. To determine whether such proliferative m phi s are immigrant or locally activated resident m phi s, mice depleted of bone marrow cells and circulating monocytes by bone-seeking radiostrontium (89Sr) were injected intraperitoneally with TG. For control (88Sr) and splenectomized (Spx) mice, more than 4 x 10(4) m phi colony-forming cells (M-CFCs) per mouse were recovered in the peritoneal lavage fluid 5 days after TG injection. 89Sr-treated mice, on the other hand, had only 20% of those in the control mice. Splenectomized and 89Sr-treated (Spx/89Sr) mice showed further depletion of bone marrow cells and monocytes and, as expected, total numbers of peritoneal M-CFCs were severely depressed to less than 1% of those in the control mice. The results suggest that levels of peritoneal M-CFCs are strongly dependent on the presence of radiosensitive bone marrow cells and circulating monocytes, and resident peritoneal m phi s activated locally by inflammatory stimuli do not form m phi colonies under the defined conditions.