High mobility group box 1 protein (HMGB1) as an immune-modulating factor for polarization of human T lymphocytes

Abstract Objective This study was performed to investigate the effect of high mobility group box-1 protein (HMGB1) on immune function of human T lymphocytes in vitro and explore its potential role in cell-mediated immune dysfunction. Methods Fresh blood was obtained from healthy adult volunteers and peripheral blood mononuclear cells (PBMCs) were isolated, then rhHMGB1 was added to PBMCs. Four-color flow cytometric (FCM) analysis was used for the measurement of intracellular cytokine including interleukin IL-4 and interferon IFN-|? ELISA kits were employed for the determination of IL-2 and sIL-2R protein levels in cell culture supernatants. Results (1) Different stimulating time and dosage of rhHMGB1 did not alter the number of IFN-? positive cells (Th1). rhHMGB1 stimulation provoked a dose-dependent and time-dependent increase in Th2 subset and decrease in ratio of Th1 to Th2. (2) Compared with the untreated cells, when the cells were coincubated with rhHMGB1 (10-100ng/ml) for 12 hrs, protein release of IL-2 and sIL-2R were significantly up-regulated. At 48 hrs, in contrast, protein production were relatively lower in cells after exposure to 100-1000 ng/ml rhHMGB1. Conclusions These findings demonstrated that HMGB1 had a dual influence on immune functions of human T lymphocytes.