Time course of CCL3 and CCL4 protein expression by CLL cells after BCR engagement. CLL cells were placed in culture medium and stimulated with 15 μg/mL anti-IgM. Supernatants were removed at the time points indicated on the horizontal axis and assayed for CCL3 (A) and CCL4 (B) protein expression by ELISA. The different symbols that are connected by the lines represent the CCL3 and CCL4 concentrations in 4 different CLL samples at the indicated time points.