title: A dissection of the CD45/side scatter "blast gate".
abstract: 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.
authors.affiliation: Department of Pathology, Medical College of Wisconsin, Milwaukee, USA.
authors.forename: Alexandra M
authors.initials: AM
authors.lastname: Harrington
authors.forename: Horatiu
authors.initials: H
authors.lastname: Olteanu
authors.forename: Steven H
authors.initials: SH
authors.lastname: Kroft
mesh_terms: D005434:Flow Cytometry / Q000379:methods*; D006801:Humans; D016130:Immunophenotyping / Q000379:methods*; D007962:Leukocytes / Q000276:immunology*; D009190:Myelodysplastic Syndromes / Q000276:immunology*