Kinetic latex agglutinometry I. A rapid, quantitative immunologic assay for fibrinogen

A rapid, convenient immunologic assay technic for fibrinogen is reported. Basically a latex agglutination, the assay technic, called kinetic latex agglutinometry, quantitates the increase in light transmission that occurs in a stirred suspension of anti-fibrinogen-coated latex beads after the addition of a plasma or whole blood sample containing fibrinogen. In this system the time "delta t" required for a given transmission change to occur is inversely proportional in a log-log relationship to the quantity of fibrinogen in the plasma sample. The reaction is linear over a fibrinogen concentration of greater than 100-fold. The sensitivity can be adjusted over a wide range, and the assay can quantitate as little as 10 ng fibrinogen. The assay can be used with either plasma or whole blood. When compared to the thrombin clotting time method of Clauss, the correlation coefficient is 0.99 for the plasma assay and 0.95 for the whole blood assay. As a one-step assay employing stable reagents and requiring approximately two minutes per assay for normal plasma, the method is ideally suited for use in the clinical laboratory.