Autoimmune thrombocytopenia purpura: platelet count less than 20,000/mm3 Adequate or increased marrow megakaryocytes Presence of detectable platelet associated immunoglobulins not due to alloreactive antibodies or posttransfusion purpura Prior response to immunosuppressive therapy Platelet count chronically less than 20,000/mm3 with petechial bleeding or less than 50,000/mm3 with other bleeding OR Any history of life threatening hemorrhage Refractory to conventional therapy for at least 21 days Splenectomy At least 1 additional immunosuppressive therapy applied after splenectomy OR Controlled on conventional therapy but at price of unacceptable toxicity: Serious steroid related toxicity Absolute neutrophil count less than 500/mm3 25% of time, pure red blood cell transfusion dependent or other toxicities (e.g., hemorrhagic cystitis) that are a consequence of chronic or cytotoxic therapy Unable to wean from chronic daily or intermittent cytotoxic therapy