Expression of MAC-1 (CD11b) in acute myeloid leukemia (AML) is associated with an unfavorable prognosis.
There is evidence to suggest, that cellular adhesion molecules and receptors could play a role in leukemia, e.g., through altered adhesive qualities of leukemic blasts. We have studied the expression of the beta2-integrin Mac-1 (CD11b) on mononuclear cells in 48 patients with AML at first diagnosis by flow cytometry using a direct fluorescein-conjugated antibody. A case was defined as positive if more than 20% of the cells expressed Mac-1. Within the FAB types, we observed a high expression rate in cases with M5 (100% MAC-1+ cases, 73% MAC-1+ cells), M4 (75% MAC-1+ cases, 48% MAC-1+ cells) and in cases with FAB-M1 with 71% MAC-1+ cases and 29% MAC-1+ cells. Separating our patients' cohort in cytogenetic risk groups, we could detect significant higher proportions of MAC-1+, cases (88% vs. 27%, P = 0.005) and cells (51% vs. 16%, P = 0.015) with poor cytogenetic risk compared to the favorable risk group. For clinical evaluations only patients treated according to the protocols of the German AML Cooperative Group (AML-CG) were included (n = 29, cases with AML-M3 were excluded). More MAC-1+ cases and cells were found in the "non-responders" group (n = 8) compared to the "responders" group (n = 24). We can conclude that AML cases with high MAC-1 expression are characterized by a worse prognosis. Evaluation of MAC-1 expression in AML might therefore contribute clinically important data with respect to develop new therapies that influence the interactions between integrins like MAC-1 on leukemic cells and endothelial or immunoreactive cells.
Medical Department 3, Klinikum Grosshadern, University of Munich, Munich, Germany.
Michaela
M
Graf
Susanne
S
Reif
Tanja
T
Kröll
Karin
K
Hecht
Volkmar
V
Nuessler
Helga
H
Schmetzer
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000097:blood*; D001752:Blast Crisis / Q000097:blood* / Q000401:mortality / Q000473:pathology / Q000628:therapy; D039481:CD11b Antigen / Q000097:blood*; D015331:Cohort Studies; D042783:Endothelial Cells / Q000378:metabolism / Q000473:pathology; D005260:Female; D015973:Gene Expression Regulation, Leukemic; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000097:blood* / Q000401:mortality / Q000473:pathology / Q000628:therapy; D016177:Macrophage-1 Antigen / Q000097:blood; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012307:Risk Factors
D014408:Biomarkers, Tumor; D039481:CD11b Antigen; D016177:Macrophage-1 Antigen