Domon L, an Immunopotentiating Agent, Acts as an NF-κB Activator

Domon L, a heat-treated component of gram-negative bacterium Achromobacter stenohalis, is used for the treatment of infectious diseases of animals. Here, we investigated the immunopotentiating potential of Domon L. In vitro studies showed that Domon L enhanced nitric oxide (NO) formation from murine macrophage RAW264.7 cells in concert with interferon (IFN)-γ. The effect of Domon L on NF-κB activation was investigated, in order to understand the molecular mechanisms of enhanced NO formation by Domon L. Domon L induced translocation of NF-κB to the nucleus in RAW264.7 cells. Induction of NF-κB dependent gene expression by Domon L was further confirmed using a transfectant containing an NF-κB-luciferase reporter gene. In vivo injection of Domon L elevated both serum IL-6 and mucoprotein, whose gene expression is party under the control of NF-κB. The spleen cells of rats treated with Domon L produced much more NO when stimulated with LPS + IFNγ than spleen cells of untreated rats. These results suggest that Domon L acts as an anti-infectious agent via NF-κB activation.