T HELPER 1 (Th1)/T HELPER 2 (Th2) CYTOKINE BALANCE IN ADULT CHRONIC IDIOPATHIC THROMBOCYTOPENIC PURPURA: RELATION TO THERAPY

Idiopathic thrombocytopenic purpura (ITP) is an autoimmune bleeding disorder characterized by destruction of antibody coated platelets in the reticuloendothelial system. Although auto reactive B lymphocytes secreting anti-platelet antibodies are considered as the primary immunologic defect in ITP, dysfunctional cellular immunity is considered important in the pathogenesis of ITP. Activated T helper cells and different T helper cytokines might play an important role in the pathogenesis of ITP. We aimed at this study to explore the pattern of Thl and Th2 cytokines (IL-2 and IL-4 respectively) and consequently T helper cell imbalance in the pathogenesis of chronic ITP. Understanding this may lead to more specific immunoregulatory therapies. Levels of IL-2, IL-4 were measured as Thl and Th2 cytokines and TGFB1 by enzyme linked immunosorbant assay (ELISA) in serum samples obtained from 68 patients with chronic ITP (20 patients untreated, 24 patients received prednisolone, 24 patients underwent splenectomy). Results were compared to 20 healthy individuals. Patients with active disease and non responders to therapy had significant higher serum IL-2, higher IL-2/ IL-4 ratio, lower IL-4 and lower TGFB1 levels than those of control group (P 0.01 and 0.001). On the other hand patients in remission had serum levels, of IL-2, IL-2/IL-4 ratio, IL-4 approaching levels of control group (P 0.05). Significant elevation ofTGFBl in patients responded to either prednisolone or splenectomy.Therapy in comparison to untreated patients (P 0.01 and 0.001 respectively) may represent a by-stander immune response in ITP patients. Our data indicate that ITP is Thl predominant disease and shifting of cytokine pattern for Thl to Th2 might be a potential immunotherapy for ITP.