FC RECEPTOR FOR IGG (FCR) ON RAT MICROGLIA

Receptor for IgG (FcR) was demonstrated on rat microglia in vivo and i n vitro by immunohistochemical staining with immune complexes of horse radish peroxidase (HRP) and rabbit IgG anti-HRP. Astrocytes, oligodend rocytes and neurons did not express FcR. Microglia in culture also sho wed FcR-mediated agglutination and phagocytosis of IgG-sensitized eryt hrocytes. A radiolabelled cDNA probe for rat FcRIII hybridized with a 1.4-kb RNA band in Northern blots prepared from total RNA from rat bra in. FcRIII mRNA-positive cells in rat brain, presumably microglia, wer e demonstrated by in situ hybridization. FcR participates in the initi ation of cytotoxic responses and of phagocytosis by microglia and is t herefore likely to be important in mediating immune reactions in the b rain.