Harmful and beneficial antibodies in immune thrombocytopenic purpura.

Two facts support the definition of idiopathic thrombocytopenic purpura (ITP) as an immune disorder. First, antibodies against platelets, which often appear after a viral infection, provoke the increased elimination of these cells. Viral disease may change the complex immune response of the host at different levels. In chronic ITP, the consequences of the dysregulated immune system are autoantibodies, primarily against platelet glycoprotein IIb/IIIa. Second, pooled immunoglobulins from healthy blood donors may influence the imbalanced immune response in ITP. The initial study dose of 5 x 0.4 g of intact 7S IgG/kg body weight can now be reduced to 2 x 0.4 g/kg body weight in the majority of patients. The possible mechanisms of action of intravenous immune globulin (IVIG) are reviewed and updated in this article. The combination of effects on the humoral and cellular immune responses using IVIG in concert with cytokines may open up new therapeutic possibilities.