β₂GPI inhibits LPS-induced TF and IL-6 expression. LPS-induced TF expression in monocytes and LPS-induced IL-6 expression in whole blood was measured in the absence or presence of plasma-purified β₂GPI or recombinant domains I to IV and V of β₂GPI. A concentration-dependent inhibition of LPS-induced tissue factor expression (▩) by plasma-purified β₂GPI (0.25-1μM) or recombinant domain V of β₂GPI (2μM) but not with recombinant domains I to IV of β₂GPI (2μM) could be observed in monocytes (A) and endothelial cells (B) after a 15-minute preincubation of β₂GPI or domain I-IV or V with LPS. Similar results were obtained with LPS-induced IL-6 expression (C), where preincubation of LPS with β₂GPI or recombinant domain V of β₂GPI, but not with domains I to IV of β₂GPI led to inhibition of the LPS induced IL-6 expression in whole blood. Data are represented as mean ± SEM relative to LPS alone (n = 3).