Measurement of plasminogen activator inhibitor 1 in biologic fluids with a murine monoclonal antibody-based enzyme-linked immunosorbent assay.
An enzyme-linked immunosorbent assay for plasminogen activator inhibitor-1 (PAI-1) in biologic fluids was developed on the basis of two murine monoclonal antibodies raised against PAI-1 purified from HT-1080 fibrosarcoma cells. The lower limit of sensitivity of the assay in plasma is 2 ng/mL. The assay is 12 times less sensitive toward the PAI-1/human tissue-type plasminogen activator (t-PA) complex as compared with free PAI-1. The intraassay, interassay, and interdilution coefficients of variation are 5.2%, 8.0%, and 7.1%, respectively. The level of PAI-1 in platelet-poor plasma of healthy subjects is 18 +/- 10 ng/mL (mean +/- SD, n = 45). In platelet-rich plasma after freezing and thawing, 92% of PAI-1 antigen is released from platelets, whereas only 8% is found in the corresponding platelet-poor plasma. In platelet-poor plasma from healthy subjects, a linear correlation (r = 0.80) was found between PAI activity and PAI-1 antigen. In plasma approximately two thirds of the PAI-1 antigen was functionally active, whereas only 5% of the PAI-1 antigen released from platelets was active. During pregnancy a progressive increase of PAI-1 antigen levels up to three- to sixfold the control value was observed. In plasma of patients with recurrent deep vein thrombosis, PAI-1 levels were 44 +/- 20 ng/mL (mean +/- SD, n = 7), during a clinically silent phase. Four of these patients had a level above 38 ng/mL (mean +/- 2 SD of normal). The present assay, based on stable and reproducible reagents, allows the specific determination of PAI-1 antigen in biologic fluids. It may facilitate interlaboratory comparisons and be useful for further investigations of the role of PAI-1 in clinical conditions associated with impaired fibrinolysis and/or a tendency to thrombosis and investigations of the role of PAI-1 in platelets.
Declerck
P J
PJ
Center for Thrombosis and Vascular Research, University of Leuven, Belgium.
Alessi
M C
MC
Verstreken
M
M
Kruithof
E K
EK
Juhan-Vague
I
I
Collen
D
D
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D002478:Cells, Cultured; D003470:Culture Media / Q000032:analysis; D004727:Endothelium / Q000032:analysis; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006023:Glycoproteins / Q000032:analysis / Q000097:blood* / Q000276:immunology; D006801:Humans; D008297:Male; D051379:Mice; D015849:Plasminogen Inactivators; D011247:Pregnancy
D000911:Antibodies, Monoclonal; D003470:Culture Media; D006023:Glycoproteins; D015849:Plasminogen Inactivators