Quantitative Analysis of Flow Cytometry Immunophenotyping Data for Aiding in the Diagnosis of Myelodysplastic Syndromes (MDS).

Recent studies have shown that flow cytometry immunophenotyping is a promising tool aiding in the diagnosis of myelodysplastic syndromes (MDS). However, the majority of these studies apply only qualitative pattern analysis in their interpretation of immunophenotypic data. The goal of this study was to analyze immunophenotyping results quantitatively, investigating the potential of this approach for providing additional information useful diagnosing MDS. Using flow cytometry immunophenotyping, we studied 56 bone marrow specimens from 13 patients with well-defined MDS by morphologic, clinical, and/or cytogenetic findings (5 RA, 3 RARS, 2 RAEB grade 1, 2 RAEB grade 2 and 1 secondary to chemotherapy), 15 cytopenic patients (controls, age-matched with MDS patients) with non-MDS/non-clonal hematologic disorders receiving marrow evaluation for other reason (ITP, fever of unknown origin, or lymphoma staging), 8 patients with AML transformed from MDS (t-AML), 6 patients with de novo AML, and 7 patients (14 specimens) with regenerating marrow after stem cell transplantation. These samples were analyzed qualitatively as reported in the literature as well as quantitatively for percentages of T-cells (CD3+), B-cells (CD20+), NK cells (CD3−/CD56+), granulocytes (moderate CD45 intensity and high side scatter characteristics), monocytes (CD14+/CD11c+), blasts (defined by dim CD45 and low side scatter, CD34+ or CD117+), erythroid precursors (CD71+/CD45−) and plasma cells (bright CD38), CD4/CD8 ratio, percentages of granulocyte subsets (CD10+, CD10−, CD36+/CD64+, CD36−/CD64+, CD11b−/CD16−, CD11b+/CD16− or CD11b+/CD16+ granulocytes per total granulocytes), percentage of CD56+ monocytes, and percentages of erythorid precursors subset (glycophorin A+ or glycophorin A- erythroid precursors per total erythroid precursors). In agreement with previous studies, qualitative analysis of these data demonstrated abnormal patterns of expression in myeloid and erythroid lineages in patients with MDS and t-AML. However, these patterns are also observed in age-matched controls and patients with de novo AML or with regenerating marrow. The quantitative analysis showed significantly increased T-cells and a significantly decreased granulocyte subset of CD11b+/CD16− in MDS patients when compared to age-matched controls (9.0 +/− 6.7% vs. 4.4 +/− 3.0 %, p = 0.023 and 28.1 +/− 14.9% vs. 44.5 +/−12.9%, p = 0.004, student t-test). There were also trends for increased NK cells and CD4:CD8 ratios and decreased total granulocytes in MDS patients as compared to the age-matched controls ( p = 0.097, 0.094 and 0.059, respectively, student t-test). Other immunophenotypic parameters demonstrated no significant differences between these two groups. Furthermore, the changes observed in MDS patients were also seen in patients with t-AML. Patients with de novo AML or regenerating marrow post stem cell transplantation showed a quantitative immunophenotypic pattern between that of MDS patients and age-matched controls. These findings suggest that quantitative analysis of flow cytometry immunophenotyping data can aid in the diagnosis in MDS as well as the identification of AML arising from background MDS. The latter is clinically significant since these patients carry worse prognosis than those with de novo AML and may require novel therapies.