Hematogones are markedly decreased in chronic myeloid leukemia: multiparametric flow cytometric analysis

Prognostic significance of flow cytometric residual disease, dysregulated neutrophils/monocytes, and hematogones in adult acute myeloid leukemia in first remission

Fifty-one consecutive non-M3 acute myeloid leukemia (AML) patients who had achieved morphologic complete remission (mCR) after induction chemotherapy were enrolled in the present study. Three characteristics of bone marrow (BM) composition analyzed by flow cytometry were combined to determine the prognostic impact. A standardized panel of reagents was used to detect residual disease of aberrant myeloid progenitor cells (RD), identify neutrophils/monocytes with dysregulated immunophenotype (dysregulated neutro/mono) and quantify the appearance of CD34(+) B-progenitor-related cluster (hematogones) simultaneously in post-induction BM of adult AML patients. Patients who had detectable RD ≥0.2 % exhibited significantly lower median leukemia-free survival (LFS) than those who did not (13.5 vs. 48.0 months; P = 0.042). Dysregulated neutro/mono abnormalities assessed by this flow cytometric scoring system (FCSS ≥2) predicted shorter LFS (8.0 vs. 39.0 months; P = 0.008). While B-progenitor-related cluster size ≥5 % predicted improved outcome, with longer LFS (not reached vs. 13.5 months; P = 0.023) and better overall survival (not reached vs. 24.0 months; P = 0.027). The proposed RD/dysregulated neutro/mono/hematogones score showed a new risk groups with different LFS in the overall patients (P = 0.0006) as well as in the subgroup of intermediate cytogenetic risk (P = 0.001). The RD/dysregulated neutro/mono/hematogones score assessed by flow cytometry for adult AML in mCR may offer a rapid and practical risk assessment providing better refinement in risk-adapted management after induction chemotherapy.

A dissection of the CD45/side scatter "blast gate"

CD45/side scatter (SS) gating is widely used for isolating blasts by flow cytometry (FC). However, other cells contaminate the "blast gate" (BG); CD45/SS gating is thus imprecise, particularly when there are few blasts. We studied the BG contents in 21 myelodysplastic syndromes (MDSs), 14 myeloproliferative neoplasms (MPNs), 7 chronic myelomonocytic leukemias (CMMLs), and 40 nonneoplastic control samples using 4-color FC with cluster analysis. There were no significant differences across groups in the median percentage of BG events represented by blasts (14.7%-22%), granulocytes (23.3%-33.2%), lymphocytes (2.1%-3.2%), and erythroids (1.0%-9.8%). Monocytes were a larger percentage of BG events in CMML (24.2%). Basophils averaged 35.4% of the BG in MPNs. The percentage of blasts within the BG averaged 94.2% in control samples vs 88.2% in MDSs and 80.7% in CMMLs. Blasts averaged about 20% of events in the BG. About 10% to 20% of blasts fell outside the BG in CMMLs and MDSs. Our data highlight pitfalls in using a traditional BG for blast analysis in nonacute myeloid disorders.