In vitro tumor-derived CCL5 chemotactic activity. (A) Surface expression of CCL5 receptors on CD14⁺ gated blood monocytes from a healthy donor. Red lines correspond to control Ig staining. Results are representative of 5 healthy donors. (B) Chemoattraction of purified human blood monocytes by the indicated DLBCL cell lines (upper left panel), in the presence of CCL5 antagonism (upper right panel) and in the presence of CCR1/CCR5 antagonism (lower left panel). An invasion assay is also shown (lower right panel). Data (mean ± standard deviation) are representative of 3 independent experiments with 3 donors. *P < .05, **P < .01 vs vehicle-treated group. The fold increase is compared with medium alone. cIg, control Ig; fluo., fluorescence.