Childhood immune thrombocytopenic purpura (ITP) is acute and generally seasonal in nature, suggesting that infectious or environmental agents may trigger the immune response to produce platelet-reactive autoantibodies 4 to 8 weeks following an infection. In general, the patient is well apart from the diffuse bruising and petechiae indicative of a profound thrombocytopenia. Over a period of 6 months, the thrombocytopenia resolves in approximately 85% of children, while the remaining 15% with persistent platelet consumption are designated as chronic ITP patients. The peak age of acute ITP is 2 to 5 years of age, a period when children experience the greatest frequency of viral infections. Children with the chronic form of ITP mirror the adult phenotype, in that females predominate, and there is no seasonal fluctuation of the disease. Evidence from our laboratory suggests that the activated platelet itself may play a role in perpetuating autoantibody production and immune dysregulation associated with ITP. Current data on lymphocyte studies and cytokine alterations noted in response to the variety of regimens used in children with ITP suggest that acute ITP is accompanied by autoantibodies to GPIb and a cytokine profile that is proinflammatory in nature. Early recognition of the immune dysregulation driving acute versus chronic ITP will distinguish those children who might benefit from immunotherapy versus those who will recover without therapeutic intervention.
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