CCL3 and CCL4 protein levels in blood plasma from CLL patients and healthy volunteers. This bar diagram displays the mean (± SEM) concentrations of CCL3 and CCL4 in 67 plasma samples from CLL patients and normal donors (n = 9), as displayed on the horizontal axis. CLL plasma displayed higher levels of both CCL 3 and CCL4 compared with normal blood plasma, suggesting that secretion of these chemokines by CLL cells occurs in vivo.