Tumor necrosis factor alpha acts as an autocrine second signal with gamma interferon to induce nitric oxide in group B streptococcus-treated macrophages.

Nitric oxide production by mouse macrophages treated with group B streptococci and gamma interferon was inhibited by cytochalasin B or by antibody neutralization of macrophage-derived tumor necrosis factor alpha. Phagocytosis-induced tumor necrosis factor alpha is responsible for group B streptococcus-induced nitric oxide production in interferon-treated macrophages.