The effect of high-dose methylprednisolone on CD34-positive bone marrow cells in the children with acute myeloblastic leukemia.

The expression of CD34 antigen on the surface of bone marrow (BM) cells during remission induction was studied in 20 patients with CD34-negative acute myeloblastic leukemia (AML). The patients were given high-dose methylprednisolone (HDMP) alone for one week, after which time mitoxantrone and low-dose Ara-C were added. BM cells from all patients were studied one, two and four weeks after initiation of treatment to evaluate CD34 antigen expression using a three-step peroxidase antiperoxidase staining technique. The mean percentage of CD34-positive BM cells was 5.3% at presentation, increasing to 15.6% in the first week, 12.9% in the second week and 21.7% in the fourth week of therapy. During the same period the mean percentages of the initial BM blasts decreased from 64% to 22%, 7% and 2% in the first, second and fourth weeks of therapy, respectively. The increase in the CD34-positive BM cells one week after HDMP treatment alone suggests that HDMP directly or indirectly stimulates CD34-positive hematopoietic progenitor cells while decreasing BM blasts in patients with AML.