Microarray Analysis of the Peripheral Monocytes From Waldenstrom's Macroglobulinemia Patients Reveals a Distinct Gene Expression Profile

Waldenstrom's macroglobulinemia (WM) is a B-cell malignancy characterized by the accumulation, predominantly in the bone marrow, of clonally related IgM-secreting lymphoplasmacytic cells. Macrophage derived inflammatory factors are elevated in WM suggesting a possible contribution by monocytes to the growth and survival of WM cells.

Monocytes (CD14⁺) from the peripheral blood of 8 untreated WM patients, and 6 healthy donors (HDs) were isolated by immunomagnetic bead sorting. Gene expression profiling was then performed using Human Genome U133 Plus 2.0 chips, and data obtained from microarray was analyzed by dChip software with fold change >=2 and p<=0.05 as cut off points. Validation was performed by real time PCR.

Using Panther classification, 284 transcripts were identified as significantly different in monocytes derived from WM patients versus HDs. The resulted transcripts are involved in many critical signaling pathways, such as Toll-like immune receptor pathway (i.e. TLR1, TLR4, TLR8, TICAM); inflammatory response (i.e. CD40, PTAFR, FPR2), integrin binding (i.e. RAC2, ILK), chemokinesis (i.e. CCR2, CX3CR1), apoptosis (i.e. TNFSF10), p53 signaling (i.e. GADD45A, 1433F) and G-protein coupled receptors (i.e. CX3CR1). Fifteen of 21 genes were validated by real-time PCR, and were over-expressed in peripheral blood monocytes from WM patients in comparison to healthy age matched donors:

Peripheral monocytes from WM patients demonstrate a distinct gene expression profile characterized by up-regulation of genes affecting Toll-like innate immunity, inflammation, and apoptosis. These studies define a distinct microenvironmental signature, and provide a framework for the exploration of novel targets for prognosis and therapy in WM.

No relevant conflicts of interest to declare.