The effect of C1INH on LPS-induced in vitro transendothelial flux. The HUVEC cell line HUV-EC-C (A) and primary HUVECs (B) were cultured in Transwell plates and treated with LPS (175 ng/mL), either alone or in the presence of C1INH (150 μg/mL). Control HUVEC cultures were treated with PBS alone as the control. Evans blue dye (20 μL, 0.5%) was added to the upper compartment and absorbance of the medium in the lower compartment was measured at 630 nm.