Immune thrombocytopenia during interferon-alfa therapy for renal cell carcinoma.

Immune thrombocytopenia is a rare complication of interferon-alfa (IFN-alpha). A patient with renal cell carcinoma developed severe thrombocytopenia during therapy with purified IFN-alpha. The patient's exposure to IFN, exclusion of other causes, and bone marrow biopsy were consistent with drug-induced immune thrombocytopenia. Cessation of IFN and corticosteroid administration resulted in the prompt recovery of platelets. The patient was re-challenged with recombinant IFN-alpha-2b under careful observation; there was no occurrence of severe thrombocytopenia. It was suggested that the difference of the subtypes composing IFN-alpha resulted in the lack of cross reactivity.