Cytokines in idiopathic thrombocytopenic purpura (ITP).

Most research in idiopathic thrombocytopenic purpura (ITP) has focused on characterization of the autoantibodies directed against platelet antigens resulting in enhanced platelet elimination by macrophages. This report summarizes the current knowledge of cytokine pattern found in individuals with ITP. Serum assessment has demonstrated increased levels of interleukin (IL)-2 and interferon-gamma (IFN-gamma), while IL-4 was significantly decreased. In addition, thrombopoietin (TPO) has been found in normal levels while IL-11 has been reported to be elevated. These data indicate that ITP is associated with a Th1 type of T helper cytokine response, while that of type Th2 is downregulated. Initially, megakaryocytes are found at normal levels in bone-marrow aspirates, explaining the unchanged production of TPO. The increase in IL-11 may be reflected by the increased number of platelets being produced per megakaryocyte. However, there is little information on these events in immunocompetent sites such as bone marrow, spleen and lymph nodes.