Circulating CD33 and its clinical value in acute leukemia.
OBJECTIVE
CD33 is a cell surface antigen for committed myelomonocytic lineage. We explored the potential of detecting CD33 as cell-free circulating protein in patients with leukemia.


METHODS
We developed a quantitative bead-based immunoflow cytometry assay to measure cell-free circulating CD33 (cCD33) levels in the plasma of patients with acute leukemia, and correlated these results with corresponding clinical behavior. We measured cCD33 levels in the plasma of 48 healthy subjects and in patients with acute myelogenous leukemia (n = 98), acute lymphoblastic leukemia (n = 46), myelodysplastic syndrome (MDS) (n = 50), and myeloproliferative disorder (n = 49).


RESULTS
Patients with acute myeloid leukemia and myeloproliferative disorders had significantly higher concentrations of cCD33 than the other patient groups and normal individuals (p = 0.0001), and among these groups, MDS patients displayed the lowest cCD33 levels (p = 0.02). Circulating CD33 values correlated positively with the CD33(+) blast cell counts in these patients. While there was no correlation between cCD33 levels and survival in acute myelogenous leukemia and MDS, higher cCD33 plasma concentrations did correlate with shorter survival in acute lymphoblastic leukemia (p = 0.03), and with shorter complete remission duration in acute myelogenous leukemia (p = 0.04) and MDS (p = 0.03).


CONCLUSIONS
Circulating CD33 can be detected in the plasma from patients with leukemias, and cCD33 levels may have clinical implication, e.g., predictive and prognostic value, in these patients.
Abdool
Adam
A
Hematology and Oncology Department, Quest Diagnostics Nichols Institute, San Juan Capistrano, CA 92675, USA.
Yeh
Chen-Hsiung
CH
Kantarjian
Hagop
H
O'Brien
Susan
S
Bruey
JeanMarie
J
Giles
Francis
F
Albitar
Maher
M
D000208:Acute Disease; D015703:Antigens, CD / Q000097:blood*; D015214:Antigens, Differentiation, Myelomonocytic / Q000097:blood*; D016022:Case-Control Studies; D045744:Cell Line, Tumor; D002474:Cell-Free System; D005434:Flow Cytometry; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000097:blood*; D063268:Sialic Acid Binding Ig-like Lectin 3
D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; C571163:CD33 protein, human; D063268:Sialic Acid Binding Ig-like Lectin 3