Expression of the myeloid-associated marker CD33 is not an exclusive factor for leukemic plasmacytoid dendritic cells.
A new entity of acute leukemia coexpressing CD4(+)CD56(+) markers without any other lineage-specific markers has been identified recently as arising from lymphoid-related plasmacytoid dendritic cells (pDCs). In our laboratory, cells from a patient with such CD4(+)CD56(+) lineage-negative leukemia were unexpectedly found to also express the myeloid marker CD33. To confirm the diagnosis of pDC leukemia despite the CD33 expression, we demonstrated that the leukemic cells indeed exhibited pDC phenotypic and functional properties. In 7 of 8 other patients with CD4(+)CD56(+) pDC malignancies, we were able to confirm that the tumor cells expressed CD33 although with variable expression levels. CD33 expression was shown by flow cytometry, reverse transcriptase-polymerase chain reaction, and immunoblot analysis. Furthermore, CD33 monoclonal antibody stimulation of purified CD4(+)CD56(+) leukemic cells led to cytokine secretion, thus confirming the presence of a functional CD33 on these leukemic cells. Moreover, we found that circulating pDCs in healthy individuals also weakly express CD33. Overall, our results demonstrate that the expression of CD33 on CD4(+)CD56(+) lineage-negative cells should not exclude the diagnosis of pDC leukemia and underline that pDC-specific markers should be used at diagnosis for CD4(+)CD56(+) malignancies.
Garnache-Ottou
Francine
F
Etablissement Français du Sang Bourgogne Franche-Comté, Unité mixte EFS/Université EA2284/Inserm U645, IFR133, Besançon, France.
Chaperot
Laurence
L
Biichle
Sabeha
S
Ferrand
Christophe
C
Remy-Martin
Jean-Paul
JP
Deconinck
Eric
E
de Tailly
Patrick Darodes
PD
Bulabois
Bénédicte
B
Poulet
Jacqueline
J
Kuhlein
Emilienne
E
Jacob
Marie-Christine
MC
Salaun
Véronique
V
Arock
Michel
M
Drenou
Bernard
B
Schillinger
Françoise
F
Seilles
Estelle
E
Tiberghien
Pierre
P
Bensa
Jean-Claude
JC
Plumas
Joel
J
Saas
Philippe
P
D000208:Acute Disease; D000368:Aged; D015703:Antigens, CD / Q000097:blood*; D015214:Antigens, Differentiation, Myelomonocytic / Q000097:blood*; D014408:Biomarkers, Tumor / Q000276:immunology; D017252:CD3 Complex / Q000097:blood; D015704:CD4 Antigens / Q000097:blood; D018958:CD55 Antigens / Q000097:blood; D003713:Dendritic Cells / Q000276:immunology*; D005434:Flow Cytometry; D006801:Humans; D016130:Immunophenotyping; D007952:Leukemia, Plasma Cell / Q000276:immunology; D008297:Male; D010950:Plasma Cells / Q000276:immunology*; D063268:Sialic Acid Binding Ig-like Lectin 3
D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D014408:Biomarkers, Tumor; D017252:CD3 Complex; C571163:CD33 protein, human; D015704:CD4 Antigens; D018958:CD55 Antigens; D063268:Sialic Acid Binding Ig-like Lectin 3