Response : Mechanisms of perforin resistance : the differentiation between perforin binding and perforin - mediated lysis remains difficult

tomized patients. For example, pretransplantation disease duration was somewhat longer (albeit not significantly so) in splenectomized patients, and although not the case in the present study, disease duration has been found to be inversely correlated with posttransplantation outcome for other indications. In addition, splenectomized patients tended to be older and more often received a transplant from an alternative donor. On the other hand, nonsplenectomized patients more often were transfusion dependent prior to transplantation.5 Without data from a large, prospective randomized trial, it is impossible to address the issue of the effect of pretransplantation splenectomy on transplantation for myelofibrosis with certainty. Such a trial is not currently available. From the present data it appears that, similar to the situation in patients not receiving transplants with agnogenic myeloid metaplasia and splenomegaly as reported by Tefferi et al,2 broad, general recommendations are difficult to formulate for patients who plan to receive a hemopoietic cell transplant. For now, the decision about splenectomy should be determined by patient symptomatology and not based on a presumed effect of splenectomy on posttransplantation outcome.