title: Measurement of factor Xa-antithrombin III in plasma: relationship to prothrombin activation in vivo.
abstract: The M(r) of the complexes formed when factor Xa reacts with antithrombin III (ATIII) in plasma were estimated by gel filtration and SDS-polyacrylamide electrophoresis. The predominant species of factor Xa-ATIII detected after plasma and plasma to which factor Xa had been added were gel filtered on Sephadex G-200 and Sepharose 4B had apparent M(r) > 200,000, in which factor Xa-ATIII was associated with vitronectin. Addition of factor Xa-ATIII to ATIII-depleted plasma also resulted in the formation of factor Xa-ATIII-vitronectin complexes with M(r) > 200,000. Using polyclonal antibodies to human factor Xa-ATIII and ATIII as the capture and detector antibodies, respectively, a sensitive and specific enzyme-linked immunosorbent assay was developed to quantify factor Xa-ATIII in plasma. The relationship between factor Xa-ATIII production and prothrombinase activity in vivo was investigated by quantifying factor Xa-ATIII and prothrombin fragment 1 + 2 endogenous to the plasmas of blood donors and patients with Hodgkin's and non-Hodgkin's lymphoma. Whereas the concentrations of prothrombin fragment 1 + 2 in the 84 normal plasmas increased with age, those of factor Xa-ATIII (mean +/- SD of 34.7 +/- 13.8 pM) did not, and no correlation existed between the concentrations of the two parameters in normal plasmas. In contrast, a highly significant correlation between the concentrations of these two parameters was found in the plasmas of the cancer patients which coincidentally also had higher concentrations of both factor Xa-ATIII and prothrombin fragment 1 + 2 than the normal plasmas. Thus, ATIII may differentially influence prothrombinase formation and activity in normal individuals and cancer patients.
authors.affiliation: Department of Pathology, McMaster University, Hamilton, Canada.
authors.forename: I
authors.initials: I
authors.lastname: Gouin-Thibault
authors.forename: L
authors.initials: L
authors.lastname: Dewar
authors.forename: M
authors.initials: M
authors.lastname: Kulczycky
authors.forename: M
authors.initials: M
authors.lastname: Sternbach
authors.forename: F A
authors.initials: FA
authors.lastname: Ofosu
mesh_terms: D000328:Adult; D000368:Aged; D000990:Antithrombin III / Q000378:metabolism*; D015153:Blotting, Western; D004797:Enzyme-Linked Immunosorbent Assay; D015951:Factor Xa / Q000378:metabolism*; D006689:Hodgkin Disease / Q000097:blood; D006801:Humans; D008228:Lymphoma, Non-Hodgkin / Q000097:blood; D008875:Middle Aged; D010949:Plasma / Q000378:metabolism; D011516:Prothrombin / Q000378:metabolism*
chemical_list: D000990:Antithrombin III; D011516:Prothrombin; D015951:Factor Xa