Gamma-interferon inhibits Fc receptor II-mediated phagocytosis of XXXX cells by @entity1 macrophages.

@entity1 @entity0 @entity5750 @entity5 @entity420 @entity379 @entity15835 @entity1722
In vitro, @entity15835 ( @entity15835 ) are capable of efficient antibody-mediated phagocytosis of @entity1 nucleated @entity5 cells. These @entity15835 express on their cell surface all three classes of Fc receptors for IgG (Fc gamma R). Fc gamma R specificity for murine antibody isotype allowed us to examine the phagocytic role of Fc gamma RII on control and gamma-interferon ( @entity379 )-primed @entity15835 . Monoclonal antibody 520C9 (IgG1) mediates phagocytosis through Fc gamma RII. This monoclonal antibody is directed against the @entity1722 protooncogene product overexpressed on a variety of @entity420 including the @entity0 cell line SK-BR-3. Our results showed that @entity379 treatment of differentiated @entity15835 (days 8-12 in culture) inhibited Fc gamma RII-mediated phagocytosis in a dose-dependent manner with negative effects noted at doses as low as 0.1 units/ml. The percentage reduction in antibody-mediated phagocytosis observed following @entity379 priming (40 units/ml for 18 h) ranged from 23-89% of control. The inhibitory effect was evident when exposure to @entity379 was transient. Fc gamma RII expression was not altered by @entity379 treatment. In our model, @entity379 did not up-regulate or down-regulate @entity1722 protein expression on our targets or affect the level of @entity5750 antigen expression on our @entity15835 . Although @entity379 is a potent activator of monocytes/macrophages and can enhance certain tumoricidal mechanisms, our data show that antibody-dependent phagocytosis through the type II Fc receptor is inhibited by @entity379 priming. Nonspecific phagocytosis was not affected.
