CCL5 receptors expressed on WM tumor cells. (A) CCL5 receptor expression (CCR1, CCR3, and CCR5) was determined by FACS analysis on BCWM.1 cells, CD19⁺CD138⁺ cells from WM patients, HS-5 cells; and primary stromal cells from WM patient by staining cells with anti-CCR1, anti-CCR3, or anti-CCR5 antibodies (white histograms); and the appropriate isotype controls (gray histograms) followed by flow cytometry analysis as described in “Methods.” This experiment was repeated 3 times with similar results. Representative histograms are shown. (B) Differential expression of mRNA in WM stromal cells. Total RNA was isolated from sorted cells and reverse transcribed. cDNA was amplified by primers for CCR1, CCR3, and CCR5. Shown is a gel from one representative donor. The expected sizes for the amplified products of CCR1, CCR3, and CCR5 are 201, 396, and 459 bp, respectively.