Patients who become infected with certain micro-organisms or who undergo surgery or suffer significant burns can develop a very serious condition termed endotoxic shock. The syndrome has severe and even fatal consequences for many patients. A similar problem occurs in many farm animals, resulting in severe economic cost to the nation. Studies using flow cytometry as a major tool are being performed to try to understand what are the critical factors in endotoxic shock and how we may more readily alleviate these symptoms.