Peripheral Blood CD34⁺ Cell Patterns in Myelodysplastic Syndromes Stratified According to International Prognostic Scoring System (IPSS).

Introduction: The International Prognostic Scoring System (IPSS) better defines the outcome and transformation risk of myelodysplastic syndromes (MDS) than FAB classification. The latter was previously found to identify different patterns of peripheral blood (PB) CD34⁺ cells in MDS. Whether a correlation exists between PB CD34⁺ cells and IPSS classification of MDS is undetermined.

Patients and Methods: PB CD34⁺ cells detected at the diagnosis of 29 MDS [according to WHO, 8 refractory anemias (RA), 7 refractory cytopenias with bi-/tri-lineage dysplasia, 5 RA with excess of blasts (RAEB)-I, 5 RAEB-II, 4 mixed MDS/myeloproliferative disorders] were compared with IPSS and its determinants [karyotype class, bone marrow (BM) blasts percentage, number of cytopenias]. Karyotype classes were as follows: good (GK): normal, isolated 5q-, 20q-, -Y; poor (PK): more than 2 anomalies, chromosome 7 abnormalities; intermediate (IK): other. Multiple group comparisons were made using Kruskal-Wallis one way analysis of variance. Continuous and categorical variables were compared by means of the Mann-Witney U test and the Fisher exact test, respectively.

Results: According to IPSS, 10 (34.5%) low risk (LR), 10 (34.5%) intermediate risk (IR)-1, 8 (28%) IR-2 and 1 (3%) high risk (HR) patients (pts) were identified, respectively. Nineteen (66%), 6 (21%), and 4 (19%) patients presented GK, IK and PK, respectively. Chromosome 7 and chromosome 17 anomalies were reported in 14% and 10% of patients, respectively. Each 5q- and -Y occurred in 7% of patients. Neutrophil counts less than 1.8 x 10(9)/L, hemoglobin less than 10 g/dL, and platelet counts less than 100 x 10(9)/L were detected in 9 (31%), 19 (66%), and 14 (48%) pts, respectively. Less than 5%, 5 to 10%, and 11 to 20% BM blasts were observed in 18 (62%), 6 (21%) and 5 (17%) patients, respectively. Median PB CD34⁺ cells were 10.4/mcL (range, 2.7–66.4). Proportion of LR/IR-1 patients with 10 or more CD34⁺ cells/mcL was significantly lower than that of IR-2/HR pts (35% vs 100%, p=0.001). In the latter, median PB CD34⁺ cells (25/mcL, range 10–66.4) were significantly higher than those detected in LR (5.6/mcL, range 2.7–10.4) and IR-1 (14/mcL, range 3.1–37.3) patients, respectively (p=0.0003 and =0.045, respectively). Median PB CD34⁺ cells in the GK group (4.7/mcL, range 2.7–15) were significantly lower than those in the IK (30/mcL, range 4.6–56) and PK (36/mcL, range 13–66.4) groups, respectively (p=0.03 and =0.01, respectively). Similarly, median PB CD34⁺ cells were significantly lower in patients with less than 5% BM blasts than in patients with 11–20% BM blasts (4.9/mcL vs 25.2/mcL, p=0.036), and in patients with 0–1 cytopenias than in patients with 2–3 cytopenias (6.2/mcL vs 16.8/mcL, P=0.023).

Conclusions: By dividing MDS according to IPSS, definite patterns of PB CD34⁺ cells can be identified. Intermediate and unfavourable karyotype, previously correlated with reduced BM CD34⁺ cell apoptosis, are also associated with high PB CD34⁺ cell counts. A prognostic impact of PB CD34⁺ cell assessment in newly diagnosed MDS is suggested.