Macrophage-colony forming cells (M-CFC), with different sensitivities to colony stimulating factors, from peritoneal exudates and tissues of chronically inflamed mice.

OBJECTIVE AND DESIGN: To determine whether nonadherent macrophage precursors are present within the inflamed peritoneal cavity in mice, we analysed the mononuclear cell populations from different peritoneal tissues.

OBJECTS: A group of 90 female mice BDF1 (C57BL/ 6 x DBA/2) was used for the study. Mononuclear cells were harvested from the peripheral blood, bone marrow, peritoneal exudate, omentum, mesentery, parietal peritoneum and diaphragm.

TREATMENT: Mice were injected intraperitoneally with 0.2 ml of Freund's incomplete adjuvant. Animals were sacrificed at 6, 13, 16, 21 and 30 days. Three to six animals were examined for each time period.

METHODS: Progenitor cell assay was performed in 1 ml of semi-solid agarose (0.3% Seakem GTG) DMEM which was supplied either with recombinant colony stimulating factors or with mesothelial cell-conditioned medium.

RESULTS: Nonadherent macrophage-colony forming cells were present in all peritoneal compartments (35-140 precursor cells/5 x 10(4) mononuclear cells). Granulocyte/ macrophage-colony forming cells were found in the inflamed omentum. Combined simultaneous treatment with GM-CSF and M-CSF blocked the proliferation of the exudate and mesentery-derived macrophage precursors, but not other peritoneal tissue-derived macrophage precursors. Sequential stimulation with GM-CSF and M-CSF did not inhibit macrophage colony formation.

CONCLUSIONS: GM-CSF can possibly influence the proliferative response induced by M-CSF. Nonadherent macrophage precursors recovered from different tissue compartments seem to differ in their sensitivity to growth regulation.