CCR5-mediated inhibition of CXCL12-induced chemotaxis by bone marrow B cells.

(A) CCL4-mediated inhibition of CXCL12-induced chemotaxis. (i) CCL4 present in the upper well only; (ii) CCL4 present in the upper and lower wells of the chemotaxis chamber. (B) Titration of the CCL4 inhibitory effect. Panel B shows a dose-response curve of CCL4-mediated inhibition of CXCL12-induced chemotaxis. Pro-B cell data are shown. Similar results were obtained for the other bone marrow B-cell subsets (pre-B, immature B, mature B cells). (C) CCL3- and CCL5-mediated inhibition of CXCL12-induced chemotaxis. (i) Inhibition of the CXCL12-induced chemotaxis by CCL3. (ii) Inhibition of the CXCL12-induced chemotaxis by CCL5. Dark bars represent the percent migration of CCL3-, CCL4-, or CCL5-treated cells relative to the migration of cells pretreated with medium alone (gray bars). The data shown in panel A are representative of 14 individual experiments, each done in triplicate. The data shown in panels B and C are representative of 4 individual experiments, each done in triplicate. The changes in chemotaxis toward CXCL12 after exposure to CCL3, CCL4, and CCL5 were statistically highly significant (*P < .005, **P < .0005, paired t test 2-sided, whereP represents a statistical difference of CCL-exposed cells compared with the control of medium-treated cells) and migration of untreated cells toward CXCL12 was considered to be 100%.