Assays for thrombosis factors: relations to plasma lipids

Several coagulation and fibrinolysis factors appear to be associated with plasma lipids in both fasting, population-based studies and postprandial studies. The molecular mechanisms for these associations, however, are not understood. There are a variety of different assays available, which can be categorized into screening assays, type 1 assays (which estimate the circulating concentration of individual zymogen, substrate, or inhibitor), type 2 assays (which measure molecular species that are formed as the result of in vivo enzymatic activity), and type 3 assays (which directly measure plasma enzymes). Although all of these types of assays have been used in human studies exploring the relation of dietary fats to thrombosis, in most cases the interpretation of the results has been hindered by one or more of the following: the potential for in vitro artifacts with blood collection, the technical limitations of clot-based assays, the different reagent systems that are available for many of these assays, and the lack of agreed-on standards. Work is needed in these areas as well as in the development of an expanded repertoire of type 2 and 3 assays, provocative tests that will allow us to determine how sensitive one's system is to procoagulant stimuli and the gene-gene and gene-environment interactions that play a role.