Interleukin-10 inhibits interleukin-2-induced tumor necrosis factor production but does not reduce toxicity in C3H/HeN mice

Immunotherapy with interleukin-2 (IL-2) is limited by severe side effects thought to be mediated by the activation of immune effector cells and the induction of secondary cytokines including tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma). In C3H/HeN mice the primary IL-2 toxicity is the production of pleural effusion with subsequent respiratory compromise. IL-10 is a cytokine that has been shown to inhibit the generation of secondary cytokines in vitro and in vivo. In this study, in C3H/HeN mice, we tested the ability of IL-10 to inhibit IL-2-induced mononuclear cell and alveolar macrophage activation and IL-2-induced increases in serum TNF-alpha and IFN-gamma, all of which may contribute to the generation of toxicity. IL-10 was ineffective at reducing IL-2-induced pleural effusion. However, IL-10 did inhibit IL-2-induced increases in serum TNF-alpha, which was accompanied by a decrease in Golgi apparatus and rough endoplasmic reticulum in alveolar macrophages. In addition, IL-10 combined with IL-2 increased mononuclear cell activation, which may limit the ability of IL-10 to inhibit IL-2-induced IFN-gamma production and pulmonary injury.