High levels of HMGB1 in plasma may be due to ex vivo cell necrosis.

BACKGROUND High mobility group box 1 protein (HMGB1) is considered an important biological marker during inflammation and malignancies. Here, we evaluated sample handling and effects of ex vivo necrosis on HMGB1 levels. MATERIALS AND METHODS Plasma samples were obtained from healthy volunteers (n=14) simulating the standard laboratory conditions, overnight incubations and harsh treatment. HMGB1 levels were evaluated by ELISA or western blot. Additionally, levels of hemoglobin, hemolysis index and lactate dehydrogenase were measured. RESULTS Plasma levels of HMGB1 were 9-fold increased in samples stored overnight at room temperature, as compared to those processed directly. The rapid centrifugation prevented the increase of HMGB1 in stored samples. Hemoglobin, hemolysis index and lactate dehydrogenase concentrations showed significant correlations with HMGB1 levels. CONCLUSION Handling of blood samples is important for the accurate estimation of systemic HMGB1. We propose that all samples with high HMGB1 concentrations should be evaluated for markers of ex vivo necrosis.