CCL5 levels correlated with IL-6 levels in WM. (A) Immunohistochemical staining for IL-6 in bone marrow biopsy specimens of 6 WM patient samples (3 with high CCL5 expression and 3 with low CCL5 expression) was performed using anti–IL-6 antibody as described in experimental procedures. Images shown are original magnification ×400. (B) Quantitative correlation of bone marrow IL-6 and CCL5 levels in bone marrow plasma samples from WM patients (n = 60). IL-6 and CCL5 levels were quantitated by ELISA as described in “Methods.” CCL5 levels were divided to high or low based on median value. (C) Average IL-6 production by HS-5 stromal cells (0.1 × 10⁶ cells/well), CD19⁺CD138⁺ cells from WM patients (0.5 × 10⁶ cells/well, n = 2 patients) and stromal cells generated from WM patients (0.1 × 10⁶ cells/well, n = 4 patients) was determined using a human IL-6 ELISA.