Objective: 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. Cell viability was assessed by thiazolyl blue (MTT) assay. Four-color flow cytometric (FCM) analysis was used for the measurement of CD3, CD8 expression. Reverse transcription-polymerase chain reaction amplification was performed to detect respective gene expression of interleukin-2 (IL-2), IL-2 receptor (IL-2R) alpha.
Results: (1)Proliferation of T lymphocytes was not affected by rhHMGB1 in low concentrations, while continued exposure of T cells to 500-1000 microg/L rhHMGB1 for 48 hours resulted in a decrease in MTT assay. (2) Different stimulating time and dosages of rhHMGB1 did not alter CD4 expression of CD3+ T lymphocytes. rhHMGB1 stimulation provoked a dose-dependent and time-dependent increase in Th2 subset and lowering in ratio of Th1 to Th2. (3) Compared with the untreated cells, when the cells were co-incubated with rhHMGB1 (10 microg/L) for 12 hours, mRNA expressions of IL-2 and IL-2R were significantly up-regulated. At 48 hours, in contrast, gene expression was relatively lower in T cells after exposure to 100-1000 microg/L rhHMGB1.
Conclusion: These data demonstrated that HMGB1 had a dual influence on immune functions of T lymphocytes.