Biochemical and pharmacological properties of a neurotoxic protein isolated from the blood serum of heavily burned patients.

Blood serum of heavily burned patients contains neurotoxic substances which are not present in normal control sera. In the present paper, we describe the purification by gel filtration and ultracentrifugation of such a neurotoxic factor. The purified factor appeared to be a high molecular weight (2 to 3.10(6) daltons) lipoprotein. This factor was present in all the sera of patients with more than 35 per cent of the body surface burned. When injected into rabbits the lipoprotein caused a flattening of the EEG tracing, then trembling and convulsions with bursts of spikes on the EEG. The activity of this neurotoxic substance was enhanced when the permeability of the blood-brain barrier was increased by previous intraventricular injection of collagenase. The presence of such a neurotoxic factor in the blood serum of burned patients, together with the increased serum collagenase activity they exhibit may explain the neurotoxic symptoms observed in them.