Concentration-dependent effect of Lp(a) on human monocyte migration. Monocytes incubated at 37°C in Hanks' balanced salt solution containing BSA 0.4% (HBSS) were permitted to migrate across polycarbonate membranes (pore size 5 μm) for 90 minutes. After fixation and staining, migrated cells attached to the lower side of the membrane were counted under the microscope using oil-immersion at a 1,000-fold magnification. **P < .01 versus basal value without chemoattractant (HBSS). Cell numbers represent the mean ± SEM of migrated monocytes per high-power field of six independent experiments. Seven fields were counted and experiments were performed in triplicate.