Effects of cytokines on Porphyromonas gingivalis-induced opsonophagocytosis of a murine macrophage cell line.

A murine macrophage cell line was incubated with opsonized Porphyromonas gingivalis and various concentrations of rIFN-gamma, rIL-4 and rIL-10. The number of phagocyted cells were microscopically assessed. The results showed that IFN-gamma upregulated macrophage phagocytosis to this periodontopathogen, and the upregulatory effects was abolished by anti-IFN-gamma antibodies. Neither IL-4 nor IL-10 had any effects on opsonophagocytosis by this cell line. These results suggest that up-regulatory functions of IFN-gamma on phagocytic activities of macrophages may play a crucial role in the induction of immune response to P. gingivalis.

Macrophage depletion in the rat after intraperitoneal administration of liposome-encapsulated clodronate: depletion kinetics and accelerated repopulation of peritoneal and omental macrophages by administration of Freund's adjuvant.

The purpose of this study was to develop a method for the depletion of macrophages from the peritoneal cavity and the omentum of the rat. Rats received two intraperitoneal injections (at days 0 and 3) with liposome-encapsulated clodronate (dichloromethylene bisphosphonate: Cl2MBP-liposomes). This treatment resulted in complete elimination of mature tissue macrophages (ED2-positive macrophages) from the peritoneal cavity and the omentum within 2 days. The elimination included the strongly ED2-positive spindle-shaped cells of the omental membrane. Repopulation of the omental ED2-positive macrophages was not seen within the next 23 days. Whereas ED2-positive macrophages were completely depleted, few ED1-positive cells remained and repopulation of ED1-positive cells was faster. The treatment further depleted macrophages from the spleen, especially from the red pulp, parathymic lymph nodes and liver. Freund's incomplete adjuvant administered one day after the last injection of Cl2MBP-liposomes considerably accelerated repopulation in the omentum. The protocol described might be used to investigate the contribution of mature tissue macrophages to the induction of immune responses, drug metabolism and the elimination of intestinal tumours.

Peritoneal cell labelling: a study on the migration of macrophages and dendritic cells towards the gut.

In this study the migration of peritoneal cells was investigated by a fluorescence labelling technique. We found that peritoneal cells migrate to the subcapsular sinus and medulla of the parathymic lymph node (PTLN) and paratracheal lymph node (PTrLN). It was also observed that fluorescence labelled cells possibly granulocytes, macrophages and dendritic cells were found in the B cell follicles of Peyer patches and the dome area after intraperitoneal (ip) labelling. The implication of the migration of antigen presenting cells to the gut on the mucosal immune response is discussed.