Plasma levels of factor XIIa and factor VIIa are increased but not relatedin primary hyperlipidaemia

The lipolysis of triglyceride-rich lipoproteins may provide a surface that supports the activation of factor XII (FXII) with subsequent activation of factor VII (FVII). Plasma levels of activated FVII (FVIIa) but not activate d FXII (FXIIa) are increased in the post-prandial state when there is a tra nsient increase in triglyceride levels. We compared plasma levels of FXIIa antigen in control subjects (n = 33) and in patients with chronically eleva ted lipids (primary hyperlipidaemia, n = 49), with FVIIa and markers of thr ombin generation. Results are given as median (first and third quartiles). Plasma levels of FXIIa [2.34 (1.68-3.32) ng/ml versus 1.53 (0.93-1.86) ng/m l, P = 0.0002], FVIIa [3.02 (2.15-4.64) ng/ml versus 2.20 (1.66-2.56) ng/ml , P = 0.0004], thrombin-antithrombin complexes [3.08 (2.16-5.54) mug/l vers us 2.13 (1.46-2.84) mug/l, P = 0.005] and prothrombin fragment 1 + 2 (Pro F 1 + 2) [1.28 (1.08-1.50)nmol/l versus 0.92 (0.65-1.08)nmol/l, P=0.0001] wer e increased compared with controls irrespective of the type of hyperlipidae mia. In hyperlipdaemic subjects, levels of Pro F1+2 were correlated with FV IIa (r=0.56, P=0.0002) and FXIIa (r = 0.31, P = 0.03). These results sugges t increased activation of both FVII and FXII in hyperlipidaemic subjects, w hich correlates with increased thrombin generation. Given the lack of corre lation between levels of FXIIa and FVIIa, it remains to be established whet her the increase in FXIIa is responsible for increased FVIIa activity in th is subject group. Blood Coagul Fibrinolysis 12:187-192 (C) 2001 Lippincott Williams & Wilkins.