ACTIVATION OF FACTOR-VII DURING ALIMENTARY LIPEMIA OCCURS IN HEALTHY-ADULTS AND PATIENTS WITH CONGENITAL FACTOR-XII OR FACTOR-XI DEFICIENCY, BUT NOT IN PATIENTS WITH FACTOR-IX DEFICIENCY

Factor VII activity (FVIIc), a risk marker for coronary heart disease, is increased during postprandial lipemia. Factor VII activation accom panies lipolysis of triglyceride-rich lipoproteins, but the nature of this association and whether it is causal remain uncertain. To explore this issue, four patients with homozygous factor XII deficiency, four with complete factor XI deficiency, six with factor IX deficiency, an d their respective age- and sex-matched controls were given two isocal oric dietary regimens, one providing on average 136 g fat and the othe r 19 g fat. Blood was taken before breakfast, immediately before lunch at 195 minutes, and at completion of the study at 390 minutes. All sa mples for each subject and matched control were assayed as one batch f or FVIIc, activated factor VII, and factor VII antigen (FVIIag). Activ ation of factor VII was observed with the high-fat regimen but not wit h the low-fat regimen in all controls, factor XII-deficient patients, and factor XI-deficient patients. No factor VII activation was observe d during either regimen in factor IX-deficient patients, but a normal postprandial responsiveness of factor VII to dietary fat was restored in one patient who replicated the study after factor IX therapy. Plasm a FVIIag was not altered postprandially in either regimen in any group of patients or controls. Factor IX apparently plays an obligatory rol e in the postprandial activation of factor VII. although the mechanism remains to be determined. (C) 1996 by The American Society of Hematol ogy