Physiologic and biologic behavior of autologous canine 131L-fibrinogen labeled by a chloramine-T method

Autologous canine 131I-fibrinogen labeled by a chloramine-T method was examined to determine whether the fibrinogen had been altered by the iodination procedure as suggested by other investigators. Before and after radioiodination, clottability of the fibrinogen was always equal to or greater than 89 percent. Gel chromatography studies revealed that labeled fibrinogen behaved as unlabeled fibrinogen and no high molecular weight material was found. Gamma camera scintigraphy reflected the chromatography results, as iodinated material did not appear in the liver or spleen until 48 to 72 hours. The slow-moving component of the whole blood clearance curves, respresenting undenatured fibrinogen, had a mean half-life of 61.4 +/- 5.1 hours (+/- S.E.M.) and comprised 51.5 +/- 7.5 percent of the initial activity. Similarly, a mean falf-life of 53.4 +/- 2.0 hours and 59.6 +/- 7.7 percent initial activity wwere attributed to fibrinogen according to the plasma clearance curves as determined by trichloracetic acid precipitation. The results clearly demonstrated that chloramine-T iodination of fibrinogen can yield an excellent product, biologically and chemically, which is free from macroaggregates.