Isolation Immunosuppressive Serum Components Following Thermal Injury

There has been increasing recognition in recent literature that immunoregulatory factors can often be detected in the serum of patients with thermal and traumatic injuries. We, too, have shown that a significant number of patients with severe thermal injuries are profoundly immunosuppressed. This immunosuppression was mediated by substances which circulate in the serum which could be easily detected using in vitro lymphocyte assays. The suppressive material was not present in normal serum, and exerted its effects through the activity of a specific (suppressor) subpopulation of lymphocytes. In this study, we have analyzed serum samples obtained from burn patients by plasmapheresis for suppressive activity, then fractionated each using Sephadex G-200. Individual fractions were tested for suppressive activity in mixed lymphocyte cultures, and approximate molecular weights established for suppressive peaks by means of chromatography calibration standards. Evidence linking suppressive activity of the sera to the presence of endotoxin, prostaglandin E, interferon, and "cutaneous burn toxin' is discussed.