Three types of macrophagic cells in the mesentery of mice with special reference to LYVE-1-immunoreactive cells.

Immunohistochemistry using whole mount preparations of the murine mesentery revealed two types of LYVE-1-immunoreactive cells with dendritic morphology other than F4/80(+) typical macrophages.The two types of LYVE-1(+) cells were regularly distributed with constant intervals throughout the mesentery and appeared to possess their own territory. Both types of LYVE-1(+) cells were weakly or moderately immunopositive for F4/80 antibody, a marker of macrophages,while F4/80(+) round macrophages were absolutely free from the LYVE-1 immunoreactivity. Only macrophages could ingest latex particles of 20 nm in diameter 3 h after a peritoneal injection.Peritoneal administration of lipopolysaccharide (LPS) induced a rapid reduction of LYVE-1 immunoreactivity in the cells with dendritic morphology followed by an increased immunoreactivity to F4/80 antibody, and simultaneously by dynamic changes in their shape. Under normal conditions,F4/80(+) macrophages in various connective tissues expressed LYVE-1, in contrast to lack of LYVE-1 in F4/80(+) macrophages within the parenchyma of visceral organs and macrophages residing in hepatic sinusoids and pulmonary alveoli. LYVE-1 may play a role in cell adhesion and migration of macrophagic cells within connective tissues rich in hyaluronan, and loss of LYVE-1 becomes a reliable sign of activated conditions in inflammation.