G-CSF-R (CD114) Expression Patterns in Normal and Malignant Hematopoiesis: Recurring Phenotypic Abnormalities in Myelodysplasia and Chronic Myelogenous Leukemia
Vidya S Hanumanthu, Samuel J Pirruccello. UNMC, Omaha, NE
Background: Myelodysplastic syndromes (MDS) and myeloproliferative disorders arise from genetic alterations affecting hematopoietic precursor proliferation, differentiation and apoptosis. We demonstrated that diagnostic flow cytometric abnormalities of myeloblast stem cell factor receptor (CD117) density are present at high frequency in MDS. We hypothesized that expression abnormalities of other growth factor receptors would also be present in these disorders.
Design: We characterized granulocyte colony stimulating factor receptor (G-CSF-R/CD114) expression in 22 normal bone marrows, 39 cases of MDS and 6 cases of chronic myelogenous leukemia (CML). The antibody cocktail CD33-FITC/CD114-PE/CD34-ECD/CD117-PC5/CD45-PC7 was evaluated on each specimen and 50,000 events were collected on a Beckman Coulter FC500. Off-line analysis was performed using Beckman Coulter CXP and Kaluza software packages. CD114 expression density and timing was evaluated on; early myeloblasts (CD33-, CD34+, CD117+), late myeloblasts (CD33+, CD34+, CD117+), promyelocytes (CD33+, CD34-, CD117+) and granulocytes (CD33+, CD34-, CD117-, high side scatter).
Results: Acquisition of myeloblast CD114 parallels CD33 with peak expression density at the promyelocyte stage. Mean fluorescence intensity (MFI) of CD114 in the normal samples was 0.7±0.1, 2.4±0.5, 3.7±0.6 and 1.2±0.2 for early blasts, late blasts, promyelocytes and granulocytes, respectively. For the 28 MDS cases which retained CD33 expression, the MFI values were 0.7±0.2, 2.5±2.5, 3.1±0.1 and 1.6±0.2 for the same differentiation stages. We found CD114 expression on 26.7±5.7% of normal myeloblasts and 34±19% of MDS myeloblasts. Four recurring phenotypic patterns were observed in the MDS cases; decreased or absent CD33 expression (11 cases), delayed acquisition of myeloblast CD114 expression (10 cases), premature acquisition of myeloblast CD114 expression (5 cases) and no discernible differences in the timing of CD114 expression (13 cases). In the CML cases we identified a specific, recurring myeloblast maturation abnormality. The CML myeloblasts exhibit peak expression density for CD33 and CD34 simultaneously on the same myeloblast subset. CD114 acquisition on this subset is then accompanied by loss of CD34. The CD33/CD34 dysmaturation abnormality was confirmed in 6 additional historical cases of CML.
Conclusions: Abnormalities in the timing of myeloblast CD114 acquisition are common in MDS. A diagnostic dysmaturation abnormality involving the timing of myeloblast CD33, CD34 and CD114 expression is present in CML.
Tuesday, March 20, 2012 9:30 AM
Poster Session III # 234, Tuesday Morning