Résumé
The objective of study was to investigate the expressions of CD80, CD86 and its ligand CD28 on peripheral lymphocytes in patients with idiopathic thrombocytopenic purpura (ITP), to explore the effect of interleukin 18 (IL-18) and its clinical significance in ITP. The expressions of co-stimulatory molecules (CD80, CD86 and its ligand CD28) on peripheral lymphocytes from 34 ITP patients and 34 normal humans were detected by immunofluorescence and flow cytometry. The IL-18 in the plasma was detected by using enzyme linked immunosorbent assay (ELISA). The results showed that the expressions of CD80 and CD86 on peripheral lymphocytes from ITP patients were higher than that of the normal control (4.21 +/- 2.27%, 7.19 +/- 5.16% vs 2.34 +/- 0.87%, 4.08 +/- 1.96%) (P < 0.01); the concentration of IL-18 in plasma of ITP patients was (538.31 +/- 111.33) pg/ml, but the concentration of IL-18 in plasma of controls was (489.44 +/- 49.07) pg/ml. The level of IL-18 negatively correlated with the platelet counts in peripheral blood (r = -0.395, P < 0.05). It is concluded that the CD28/CD80 and CD28/CD86 costimulatory molecules are overexpressed, when the IL-18 level in ITP patients is obviously higher than that in normal controls. When ITP occurred, and the co-stimulatory molecules CD80 and CD86 are closely associated with ITP, it seems that IL-18 may play an important role in ITP pathogenesis.