Expression of HMGB1 in Spleen of Adult Patients with Chronic and Refractory Immune Thrombocytopenia and Its Significance

OBJECTIVE: To investigate the expression and clinical significance of high mobility group box 1(HMGB1) in spleen of adult patients with chronic and refractory immune thrombocytopenia(ITP). METHODS: Twenty chronic and refactory ITP patients received splenectomy were enrolled in ITP group and 20 cases of traumatic spleen rupture were enrolled in control group. The splenectomy efficacy in ITP patients was analyzed retrospectively. The HMGB1 expression in spleen tissue was detected by immunohistochemistry, and the correlation between different expression levels of HMGB1 and splenectomy efficacy were analysed. Meanwhile, the protein expression levels of HMGB1 in peripheral blood serum and mononuclear cells(PBMNC) of 25 patients with chronic and refractory ITP were detected by ELISA and Western blot. RESULTS: The median platelet count before splenectomy was 7.5 (0-20) ×109/L; all the patients showed that the initial response to splenectomy within the first month after operation was 100%, the median time of response was 1 day (1-6 days). The median peak platelet count post splenectomy was 448.5 (161-1272)×109/L. In the median time of 10(3-30) months, the platelets count in 8 patients was reduced to varying degrees. After a median follow-up of 69.5 months (22-195), complete response was found in 12 patients, 4 cases showed response and 4 did not. The HMGB1 expression positive rate in spleen of ITP patients was significantly higher than that in control group (85.0% vs 15.0%)(P<0.001). There were a negative correlation between the HMGB1 expression in ITP and therapeutic outcome after splenectomy (r=-0.791, P<0.01). In addition, HMGB1 expression levels in serum and PBMNC of the patients with chronic refractory ITP were also significantly higher than that in healthy controls (P<0.01). CONCLUSION: The splenectomy has been found to be effective therapeutic method for patients with ITP, the HMGB1 highly express in the spleen of the patients with chronic refractory ITP, but negatively correlats with the therapeutic outcome after splenectomy.