We conducted a phase II study of the intravenous administration of a glycosylated recombinant human granulocyte colony-stimulating factor (rhG-CSF) for 7-14 d in 41 patients with the myelodysplastic syndromes (MDS). Administration of rhG-CSF elicited striking rises in both leucocyte and neutrophil counts in the majority of the patients irrespective of the FAB subtypes of MDS. The rises in neutrophil counts were dose dependent and 5 micrograms/kg/d of rhG-CSF yielded approximately an 8-fold increase in neutrophil counts. Leucocytes and neutrophil counts started to increase shortly after the first injection of 5 micrograms/kg, was maintained at significantly elevated levels during 14 d of treatment, and returned to the pretreatment levels within several days following discontinuation of rhG-CSF. The action of rhG-CSF was specific for neutrophils since leucocytosis was due exclusively to neutrophilic increase associated with an increased marrow myeloid maturation. There were no consistent changes in the monocyte, eosinophil, lymphocyte, platelet or reticulocyte counts. After treatment, the percentage of marrow blast cells was reduced in eight of 13 evaluable patients with refractory anaemia with an excess of blasts (RAEB) or RAEB in transformation (RAEB-t). No patients developed acute leukaemia during the treatment or in the immediate follow-up period. The treatment was well tolerated with only minimal toxicity. The results suggest that rhG-CSF is a safe and effective way to promptly improve neutropenia in MDS patients.
Chromosomes of mouse myelocytic leukemias that developed in 7 irradiated mice, 3 C3H/He males, 1 RFM female, and 3 RFM males were analyzed with chromosome-banding techniques. Chromosomes No. 2 were partially deleted in 6 of the 7 mice. Although the deleted No. 2 chromosomes varied in size in the 6 mice, one common characteristic was noted in all these deletions: A segment lying between a certain band in the region 2C and a band in the region 2E, including the whole region 2D, was missing. Another consistent abnormality was an addition or a loss of the Y-chromosomes in the fraction of cells in all 6 males. In addition to these consistent abnormalities, various chromosomes had structural abnormalities. The RFM female, which did not have the abnormal No. 2 chromosome, had abnormalities in chromosomes No. 3, 4, 11, 12 and 15 and in the X-chromosome. Of the 20 chromosome pairs, only such chromosomes as No. 1, 5, 8, 14, 17, and 19 and the Y-chromosome did not have the structural abnormalities. The possible role of the partial deletion of the No. 2 chromosome was considered in relation to the development of mouse myeloid leukemias.
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