The CM resulting from incubation of Lp(a) (LCM) or recombinant 6K apo(a) (KCM) with HUVECs induces chemotaxis of HUVECs that is inhibited by polyclonal antibodies against I-309 or CCR8.

The CM obtained following incubation of medium 199 (CM), Lp(a) (150 μg/mL; LCM), or a recombinant apo(a) derivative containing 6 type 4 kringles, kringle V, and the protease domain (40 μg/mL; KCM) with HUVECs for 6 hours at 37°C, were tested for HUVECs transmigration as described in “Materials and methods.” Medium 199 (M), Lp(a) (150 μg/mL), or the apo(a) derivative (6K; 40 μg/mL) was used as a control. Polyclonal goat anti-I-309 (1 μg/mL) was added to the CM, or polyclonal goat anti-CCR8 (1 μg/mL) was added to the indicator endothelial cells prior to testing as indicated in the figure. Neither Lp(a) nor the 6K apo(a) derivative directly induced HUVECs transmigration as compared to the medium 199 control. LCM and KCM induced endothelial cell transmigration as compared to the CM (*P < .001). Anti-I-309 and anti-CCR8 inhibited endothelial cell transmigration induced by LCM and KCM to the constitutive activity induced by the HUVEC CM. hpf, high power field.