Clinical value of bone marrow cultures in childhood pure red cell aplasia.

PURPOSE: We assessed the value of marrow cultures for defining the pathophysiology, diagnosis, and therapeutic response to immunosuppressive therapy in childhood pure red cell aplasia (PRCA). PATIENTS AND METHODS: Patients were evaluated either at diagnosis (n = 23) or at the time of treatment failure (n = 2). Twelve patients had transient erythroblastopenia of childhood (TEC), 4 had Diamont-Blackfan anemia (DBA), and 9 had acquired sustained PRCA (A-Su-PRCA). Bone marrow mononuclear cells were cultured with combination of human recombinant (rhu) erythropoietin (EPO), granulocyte monocyte colony stimulating factor (GM-CSF), granulocyte colony stimulating factor (G-CSF), Interleukin 3 (IL-3), either with or without stem cell factor (SCF), and burst forming unit of erythroid (BFU-E) growth was assessed. RESULTS: The combination of growth factors without SCF failed to induce any erythropoiesis (BFU-E < 10/10(5) mononuclear cells) in 10 patients (2 with TEC, 2 with DBA, and 6 with A-Su-PRCA), although the growth of erythroid colonies was substantially lower in the remaining patients than in controls (45.5 +/- 15.4 versus 91.7 +/- 12.7, p < 0.05). Addition of SCF restored erythropoiesis in all but 6 patients (5 with A-Su-PRCA and 1 with DBA). Five of 6 nonresponders did not respond to any immunomodulating therapy; of the 5, 3 had or developed some evidence of myelodysplasia. CONCLUSION: Our data indicate that in vitro colony studies might prove to be a useful diagnostic tool, because erythropoiesis' poor response to growth factors, including SCF, may suggest the diagnosis of myelodysplasia. Moreover, it may have predictive value; in cases of PRCA, regardless of etiology, poor growth of erythropoietic colonies may predict refractoriness to immunomodulating therapy.