Sepsis-induced SOCS-3 expression is immunologically restricted to phagocytes

Abstract: We have shown that immune cells from septic mice exhibit a suppressed response to exogenous stimuli in vitro. The suppressors of the cytokine signaling (SOCS) family are proteins that block intracellular signaling and can be in-duced by inflammatory mediators. Therefore, we hypothesized that SOCS-3 is up-regulated in im-mune cells in response to a septic challenge in-duced by cecal ligation and puncture (CLP). Mice were subjected to CLP or sham-CLP, and 2–48 h later, the blood, thymus, spleen, lung, and peritoneal leukocytes were harvested and examined. SOCS-3 was undetectable in thymo-cytes or blood leukocytes. In contrast, SOCS-3 was up-regulated in the spleen, lung, and perito-neal leukocytes in a time-dependent manner. Further examination revealed that only the mac-rophages and neutrophils expressed SOCS-3. These data suggest that cytokines and bacterial toxins present during sepsis have the ability to suppress the cytokine and/or lipopolysaccharide response and the function of immune cells b