Activated factor VII in amniotic fluid induces an increase in barrier function of TF exposing immortalized human keratinocytes. (A) HaCaT lysate was blotted for TF. Lysates from human platelets and brain were used as negative and positive controls, respectively. (B) Citrate-anticoagulated human plasma was added to HaCaT cells, and clotting time was monitored after recalcification in the absence and presence of a TF antibody (clone HTF-1). (C) TEER of HaCaT cells was measured after addition of human factor VIIa (FVIIa) to HaCaT cells. (D) AF and (E) Sepharose 2B-size exclusion chromatography (SEC2B) separated AF fractions 8 to 10, and 18 to 20 were added to HaCaT cells before measuring TEER. (F) The effect of AF SEC2B fractions 18 to 20 on TEER was measured in the absence and presence of 3 different monoclonal anti-FVII antibodies (CLB, 12C7, and 3G12), which block different specific epitopes of FVII(a). (G) A lucifer yellow rejection assay was performed with AF SEC2B fractions 18 to 20 in the absence and presence of anti-FVII antibodies. All measurements were performed in triplicate. Buffer was used as control. ∗P < .05; ∗∗P < .01; ∗∗∗P < .001; AF, amniotic fluid; AUC, area under the curve; TEER, transepithelial electrical resistance; n.s., nonsignificant.