Immunophenotypic Diagnostic Score for MDS Taking into Account Various Cell Populations.

Immunophenotyping has proven to be an interesting approach in patients with myelodysplastic syndromes (MDS)(Maynadie et al., Blood. 2002 Oct 1;100(7):2349–56). Most studies in these diseases have focused on the analysis of blast cells. We chose to determine the potential interest of markers expressed on other bone marrow compartments, namely granulocytes, monocytes and the CD34 compartment.

Fourteen marrow samples from patients with MDS and 10 normal bone marrow were analyzed. The median age in the MDS group and the control group was 64.4 and 59.8 years, respectively. Flow cytometry analysis of bone marrow samples was performed on a Facs Calibur, using four-color panels. The following antigens were analyzed: CD7, CD11c, CD14, CD15, CD16, CD33, CD34, CD45, CD36, CD38, CD56, CD71, CD117 and HLA-DR. The various compartments analyzed were defined using CD45/SSC gating, combined with SSC/CD34 gating for CD34+ cells. The median percentage of blasts in the MDS marrows was < 5%. Seven patients had a hemoglobin value < 100 g/dl. Five patients had a leukocyte count < 3.10⁹/l. Six patients had a platelet count < 100.10¹²/L. Threshold values were determined by ROC analysis. Comparison of the expression levels of markers between MDS and normal bone marrows was performed using a Wilcoxon test. Analysis was performed on bone marrow granulocytes, monocytes and CD34 cells.

Granulocytes were found to express higher levels of CD33 in MDS than in normal marrows (p=0.007). CD34 + cells in MDS marrows expressed significantly higher levels of CD11c (p=0.007), CD117 (p=0.023) and CD33 (p=0.013) than their normal counterparts, with a trend towards lower expression of CD71 (p=0.053). Monocytes in MDS marrows expressed significantly lower levels of CD16 (p=0.006), CD36 (p=0.004) and CD117 (p=0.007) than their normal counterparts, with a trend towards lower expression of CD11c (p=0.059). We did not observe any differences in the antigen expression of MDS erythroblasts in comparison to their normal counterparts. A diagnostic score (0–7) was constructed taking into account the following seven parameters: expression of CD33 on granulocytes; CD11c, CD33 and CD117 on CD34+ cells; CD16, CD36 and CD117 on monocytes. This score distinguished all cases of MDS samples from controls. These results suggest that analysis of cell populations other than blasts could be useful in patients with MDS and that an immunophenotypic panel composed of markers commonly used in the diagnosis of acute leukemias could constitute a useful tool, in complement to morphological studies, for the diagnosis of myelodysplastic syndromes.