Prognostic Significance of CD33, CD34 and CD117 Expression on Bone Marrow Blasts of Patients with Myelodysplastic Syndromes.

Introduction: Although blast-rich specimens immunophenotype studies in myelodysplastc syndromes (MDS) could associate bone marrow (BM) blast expression of CD7 and/or CD117 antigens with poor outcome (Ogata et al., Blood 2002), the prognostic role of markers of myeloid cell immaturity and committment in not enriched BM samples is largely unexplored.

Patients and Methods: The expression of CD33, CD34 and CD117 antigens in not enriched BM samples of 50 newly diagnosed MDS was compared with both BM blast WHO category and IPSS score. Immunophenotyping was carried out by using the panel of quadruple monoclonal antibodies CD34/CD117/CD45/CD33, conjugated with the fluorochromes FITC, PE, PerCP, APC, respectively. Acquisition of information on 1x10⁵ stained cells corresponding to the whole BM cellularity was assessed on a dual-laser FACSCalibur flow cytometer using the CellQUEST software (Becton Dickinson, San José CA USA). Multiple group comparisons were made using non parametric ANOVA for BM blasts; general linear model with Wald’s test and Kruskal-Wallis (KW) test to confirm significance was used for IPSS.

Results: According to IPSS, 5 (10%) low risk, 27 (54%) intermediate risk-1, 14 (28%) intermediate risk −2 and 4 (8%) high risk pts were identified, respectively. The expression of CD33, CD34 and CD117 significantly correlated with both blast WHO category and IPSS, as shown in the Table 1. Interestingly, by analyzing the subset of 30 pts with BM blasts <5%, a correlation was found between IPSS and the expression of both CD33 (p=0.0097) and CD34 (p=0.0299); CD117 expression increased in pts with higher IPSS, without, however, reaching statistical significance.

Conclusions: Both markers of myeloid cell committment (i.e., CD33 and CD34) and markers of myeloid cell immaturity (i.e., CD117) correlate with BM blast WHO category and IPSS score. Expression of CD33 and CD34 may have prognostic significance independently from blast percentage. The evaluation of CD33, CD34 and CD117 expression on not enriched BM samples may represent a simple tool for the prognostic assessment of MDS patients, in addition to previously established methods.

Tab. 1:

Correlation of CD33, CD34, CD117 expression with IPSS and percentage of BM blast in 50 MDS pts at diagnosis

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