Adoptive transfer of fluorescence-labeled cells shows that resident peritoneal macrophages are able to migrate into specialized lymphoid organs and inflammatory sites in the mouse.

We have examined the migration of murine macrophages from the vascular compartment to normal and inflammatory tissues by the adoptive transfer of resident peritoneal macrophages (RPM phi) fluorescently labeled with the hydrophobic dye 1,1'-dioctadecyl 3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI). After initial labeling of the plasma membrane of RPM phi, the dye accumulated stably in intracellular vesicles of low density (rho = 1.042-1.045 kg/l) and cells remained viable in culture for 4 weeks. Like the normal monocyte, DiI-RPM phi, but not exudate-derived or fixed cells, migrated to peritoneal exudates, following i.v. adoptive transfer, by a mechanism inhibitable by an antibody to the type 3 complement receptor. In the absence of an inflammatory stimulus there was no migration to the peritoneal cavity, and DiI-RPM phi accumulated within 4 h in the red pulp and marginal zone of the spleen. By day 6 these cells still formed a tight ring of fluorescence in the marginal zone alone, outside the marginal metallophil cells. DiI-RPM phi injected into the peritoneal cavity migrated to the parathymic lymph nodes where they were found in the subcapsular sinus and in the medullary cords, whereas very few fluorescent cells could be found in the T cell areas. The migration of RPM phi to lymphoid organs required viable cells but, unlike the recruitment of cells to peritoneal exudates, was not inhibitable by antibodies to CR3. We conclude that the RPM phi is a useful surrogate for the analysis of constitutive and induced monocyte migration to secondary lymphoid and inflammatory sites, respectively.