The myeloproliferative disorders. Correlation between clinical evolution and alterations of granulopoiesis.

Patients with myeloproliferative disorders were prospectively studied by in vitro agar-gel marrow culture technics to evaluate factors involved in the evolution of abnormal granulopoiesis. Marrow granulocytic colony-forming capacity was determined in 78 patients with chronic myeloid leukemia, subacute myeloid leukemia, preleukemia, Di Guglielmo's syndrome, polycythemia vera or essential thrombocythemia. A wide range of marrow colony-forming capacity values was noted early in disease courses; however, in 26 of 33 patients decreased colony-forming capacity was associated with disease transformation into acute myeloid leukemia or other clinically aggressive stages. An increased proportion of abnormally light buoyant density (less than 1.062 g/cm3) colony-forming cells was present in the marrow and peripheral blood of 15 of 16 patients with chronic myeloid leukemia, subacute myeloid leukemia, preleukemia or essential thrombocythemia; in seven of eight patients with greater than 35 per cent abnormally light colony-forming cells their disease subsequently underwent transformation. Elevated levels of urinary colony-stimulating factor output were noted in 17 of 31 patients, and in 10 of 12 patients whose disease subsequently underwent acute transformation within 10 months of study. In six of seven patients who simultaneously had an increased urinary output of colony-stimulating factor and low colony-forming capacity in marrow, transformation occurred within 10 months. These findings indicate that progressive abnormalities of both marrow clonal growth patterns and levels of possible humoral regulatory substances develop during evolution of these diseases. In contrast, patients with idiopathic sideroblastic ineffective erythropoiesis had normal values for marrow colony-forming capacity, proportion of light density colony-forming cells and urinary colony-stimulating factor output, and in none has their disease transformed into acute myeloid leukemia. These in vitro studies appear useful for clinical staging, evaluating prognosis and categorizing patients with myeloproliferative disorders.