Distinctions between microglial cells and peripheral macrophages with regard to adhesive activities and morphology

Activated microglial cells and peripheral macrophages are hardly distinguis hable from the viewpoints of morphology and function, There are various imm unological markers common to both microglial cells and peripheral macrophag es. In the present study, however, we found that microglial cells have dist inct characters in terms of adhesion and morphology, By using a "rheoscope, " that is an apparatus to theologically measure the strength of cell adhesi on to substrates, rat microglial cells were found to attach to polystyrene dishes much more weakly than alveolar and peritoneal macrophages. Interfero n-gamma (IFN gamma) strengthened the adhesion of alveolar and peritoneal ma crophages, whereas it weakened that of microglial cells. Morphological chan ges of microglial cells induced by IFN gamma were also different from those of peripheral macrophages. Furthermore, alveolar and peritoneal macrophage s produced NO in response to IFN gamma, while microglial cells did not. Whe n cultured on astrocyte-derived extracellular matrix (AsECM) in serum-free medium, only microglial cells extended multiple ramified processes. Convers ely, alveolar and peritoneal macrophages on AsECM shrunk their ruffling mem brane and rounded up, These distinctions between microglial cells and macro phages may reflect differences in cell lineages as well as environments in which individual cells reside. (C) 1999 Wiley-Liss, Inc.