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Exudation of proliferative macrophages in local inflammation in the peritoneum
Y Oghiso1, Y Yamada, Y Shibata
1Division of Comparative Radiotoxicology, National Institute of Radiological Sciences, Chiba, Japan.
Abstract:
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.
Insights
Thioglycolate-elicited macrophages form colonies, but resident macrophages do not. Bone marrow cells and monocytes are crucial for peritoneal macrophage colony-forming cells (M-CFCs) following thioglycolate stimulation.
Area of Science:
- Immunology
- Cell Biology
Background:
- Thioglycolate (TG)-elicited peritoneal macrophages (m phi s) exhibit high proliferation and colony formation in vitro with macrophage colony-stimulating factor (M-CSF).
- Resident peritoneal macrophages do not display this proliferative capacity under similar conditions.
Purpose of the Study:
- To investigate whether proliferative macrophages in the peritoneum after TG injection are derived from immigrant bone marrow cells or locally activated resident cells.
Main Methods:
- Mice were depleted of bone marrow cells and monocytes using bone-seeking radiostrontium (89Sr).
- TG was injected intraperitoneally into control (88Sr), splenectomized (Spx), and Spx/89Sr-treated mice.
- Peritoneal lavage fluid was collected 5 days post-injection to quantify macrophage colony-forming cells (M-CFCs).
Main Results:
- Control and Spx mice showed over 4 x 10(4) M-CFCs per mouse after TG injection.
- 89Sr-treated mice exhibited only 20% of the M-CFCs found in control mice.
- Spx/89Sr-treated mice displayed severely depressed M-CFC levels, less than 1% of control levels.
Conclusions:
- Peritoneal M-CFC levels are highly dependent on radiosensitive bone marrow cells and circulating monocytes.
- Locally activated resident peritoneal macrophages do not form colonies under the experimental conditions, suggesting immigrant cells are the source of M-CFCs.