Elevated expression of IL-12 and IL-23 in patients with primary immune thrombocytopenia

Immune thrombocytopenia (ITP) is an acquired autoimmune disorder. Both impaired platelet production and T-cell-mediated effects play a role in ITP. A T-helper1 (Th1) polarization of the immune response and up-regulation of Th17 cells have been demonstrated in ITP patients. Interleukin (IL)-12 and IL-23 produced by antigen presenting cells are essential for inducing and sustaining Th1 and Th17 effector cells via different pathways. However, less is known with regard to the levels of expression and synthesis of these two cytokines in patients with ITP. This was determined in this study in 46 patients with ITP as well as in 22 healthy controls. Our results showed that an increased expression of IL-12 p40, IL-12 p35, and IL-23 p19 mRNA was observed in bone marrow mononuclear cells and peripheral blood mononuclear cells of patients with ITP compared with controls. Consequently, higher levels of IL-12 and IL-23 were also found in bone marrow plasma and peripheral blood plasma in patients with ITP than in controls. Afterwards, a markedly higher level of IL-12 and IL-23 in bone marrow plasma or peripheral blood plasma was found in patients with chronic ITP than in patients with acute ITP Furthermore, the peripheral blood plasma levels of IL-12 and IL-23 were negative correlated with platelet counts in ITP patients. Therefore, the augmented expression of IL-12 and IL-23 in patients with ITP may play an important role in the pathogenesis of this disease.