Immunoglobulin G1 immune complex upregulates interferon-γ-induced nitric oxide production via ERK1/2 activation in murine microglia

Intrathecal Immunoglobulin G (IgG) is elevated in some central nervous system (CNS) diseases and microglia upregulate Fcγ receptors in various neurological disorders. However, the interaction between IgG or IgG immune complexes and microglial Fcγ receptors is not fully understood. In this study, the effect of IgG1 immune complexes on microglia was investigated. IgG1 immune complexes increased nitric oxide production in murine microglia in the presence of interferon (IFN)-γ. These effects were dependent upon IgG1 immune complex-induced activation of spleen tyrosine kinase with subsequent activation of extracellular signal regulated kinase1/2. Collectively, these results indicate that IgG1 immune complexes can exert immunomodulatory effects in various central nervous system disorders.