Soluble interleukin-2 receptor (sIL-2R) was measured in the plasma of 31 patients with idiopathic thrombocytopenic purpura (ITP) and 22 normal controls. When thrombocytopenia persisted longer than 6 months, the diagnosis of chronic ITP was made. Twenty patients had acute ITP, 11 patients had chronic ITP, and all patients received high-dose methylprednisolone (HDMP) (30 mg/kg/d for 3 days, 20 mg/kg/d for 4 days). The sIL-2R levels of the patients were determined before being giving HDMP and 14 days after the end of HDMP therapy. Platelet counts were determined before administration of HDMP, one day after the end of HDMP therapy, and once every 28 days for 7 months thereafter.
There was not a significant difference between the mean pre-treatment plasma sIL-2R levels of both acute and chronic ITP groups (P > 0.05), and these were higher than that of the control group (P < 0.001). The mean post-treatment sIL-2R level of the chronic ITP group was significantly higher than those of both the control and post-treatment acute ITP groups (P < 0.001). There were negative correlations between the plasma sIL-2R levels and platelet counts of both group patients in the pre-treatment period and between post-treatment sIL-2R levels and platelet counts in chronic ITP group (P < 0.05).
We think that there was a good correlation between prognosis of ITP and sIL-2R levels after HDMP therapy, and platelet counts in patients with ITP are linked to sIL-2R levels.