TNF and multiple sclerosis: It has been shown that IVIg reduce phagocytosis in vitro via Fc receptors [13], IVIg induce tumor necrosis factor-α (TNF-α) and nitric oxide (NO) in a dose-dependent manner, whereas the greater the IgM/IgA content the higher the impact on microglial cells [14], and that IVIg enhance the secretion of matrix metalloproteinase 9, which seems to play a role in the pathogenesis of multiple sclerosis [15].