ACTIVATED PROTEIN-C-ALPHA-1-ANTITRYPSIN (APC-ALPHA-1AT) COMPLEX AS A MARKER FOR INVITRO DIAGNOSIS OF PRETHROMBOTIC STATES

The purpose of the study was to test whether APC:alpha(1)AT complex is a useful clinical marker of the activation of coagulation. The rationale for this is that activated protein C may appear in circulation at an early stage of blood coagulation, when subcoagulant amounts of thrombin are formed. Given the relatively higher half-life of APC:alpha(1)AT as compared to that of thrombin:AT-III (TAT) complexes, we hypothesized that APC:alpha(1)AT could represent an amplification of the thrombin generated in the first events of coagulation. Using sandwich ELISA's we measured APC:alpha(1)AT and TAT complexes as well as complexes of AT-III with its target proteases in normal subjects and in several clinical groups of patients prone to thrombotic episodes, including pregnancy, preeclampsia, hemodialysis, gynecological tumors, diabetes and oral contraceptives. APC:alpha(1)AT complex was significantly increased in all clinical groups as compared to normal subjects and showed relatively higher increases than did TAT and ATM complexes in the majority of the groups studied. There was a significant and positive correlation between APC:alpha(1)AT and TAT complex levels in the majority of the groups, as well as between TAT and ATM and between APC:alpha(1)AT and ATM complex levels. We conclude that APC:alpha(1)AT complex can be used as a sensitive marker of prethrombotic states.