Combined flow cytometric assessment of CD45, HLA-DR, CD34, and CD117 expression is a useful approach for reliable quantification of blast cells in myelodysplastic syndromes

Background. Quantification of bone marrow (BM) blasts by cytomorphology is essential for the diagnosis of myelodysplastic syndromes (MDS). Owing to its subjectivity and the potential impact of dysplastic features on accurate identification of blast cells, more objective approaches are required, multiparameter flow cytometry (MFC) being a particularly promising approach in this regard. However, no consensus exists about the optimal combination of markers and strategy to be used. Methods. BM blast counts from 74 MDS patients were evaluated by morphology versus four different MFC phenotypic criteria: CD34+, CD34+ and/or CD117+, CD34+, and/or CD117+HLA-DR+, and CD34+ and CD117+HLA-DR+ plus CD64+CD14/lo cells. for each criterium, the percentage of blasts was calculated using either all BM nucleated cells or non-erythroid CD45+ cells as denominator. Results. the number of CD34+ and/or CD117+HLA-DR+cells showed the highest correlation and agreement with morphological counts, only a minor proportion of cases being misclassified by MFC vs. morphology for the >5% and >10% classification thresholds. in turn, a CD34+ phenotype was insufficient to correctly identify and quantify blasts. Conversely, usage of non-erythroid BM cells as denominator, or inclusion of CD34+ and/or CD117+HLA-DR+ plus CD64+CD14lo cells were both associated with overestimated blast counts. Conclusions. Quantification of CD34+ and/or CD117+HLA-DR+ cells (from all nucleated BM cells) by MFC is an efficient method for the enumeration of blasts in MDS. However, caution should be taken with replacing morphology by MFC blast counts; its combined use may rather provide complementary information increasing the accuracy and reproducibility of BM blast cell counts in these patients. (c) 2013 International Clinical Cytometry SocietyFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)FADA UNIFESPRTICCFondo Europeo de Desarrollo Regional (FEDER), the Instituto de Salud Carlos III, Ministerio de Economia y Competitividad, Madrid, SpainUniversidade Federal de São Paulo UNIFESP EPM, Div Hematol, Dept Clin & Expt Oncol, Escola Paulista Med, São Paulo, BrazilUniv Salamanca, CSIC USAL, Ctr Invest Canc IBMCC, E-37008 Salamanca, SpainUniv Salamanca, Serv Citometri, IBSAL, E-37008 Salamanca, SpainUniv Salamanca, Dept Med, E-37008 Salamanca, SpainUniversidade Federal de São Paulo UNIFESP EPM, Div Hematol, Dept Clin & Expt Oncol, Escola Paulista Med, São Paulo, BrazilFAPESP: 05/57792-0CNPq: 142968/2006-4CAPES: PDEE BEX 1025/05-8RTICC: RD12/0036/0048Web of Scienc