ANALYSIS OF CD34-POSITIVE CELLS IN BONE-MARROW FROM PATIENTS WITH MYELODYSPLASTIC SYNDROMES AND ACUTE MYELOID-LEUKEMIA AND IN NORMAL INDIVIDUALS - A COMPARISON BETWEEN FACS ANALYSIS AND IMMUNOHISTOCHEMISTRY

In patients with myelodysplastic syndromes (MDS) and acute myeloid leu kemia (AML), expression of the hematopoietic stem cell marker CD34 has been associated with a poorer prognosis. CD34 is usually analyzed by flow cytometry (FC), but may also be analyzed using immunohistochemist ry (IH). The present study was undertaken to compare these 2 methods. Bone marrow from 16 patients with MDS and 12 with AML and from 12 heal thy young volunteers was studied. The expression of CD34 was analyzed with FC on fresh bone marrow cells and with IH on sections of paraffin -embedded bone marrow. The correlation between FC and IH was good both for patients with MDS (p<0.0001) and AML (p<0.01). However, in patien ts with a high number of CD34-positive cells, the FC method seemed to result in a higher percentage of positive cells compared to the IH met hod. In normal bone marrow, the ratio between the percentage of CD34-p ositive cells and the percentage of bone marrow blasts was approximate ly 0.8, In the whole group of MDS patients, this ratio was 1:1, while in patients with refractory anemia (RAI and ring sideroblastic anemia (RAS) it was 1.6, Patients with MDS differed significantly from patien ts with de novo AML, who showed a ratio of only 0.23 (p<0.01). We conc lude that the FC and IH methods for measuring expression of CD34 are w ell-correlated in MDS and reasonably well correlated in AML. A stem ce ll phenotype is more commonly expressed on precursor cells from patien ts with MDS than from patients with AML.