FORMATION AND DISSOCIATION OF SOLUBLE FIBRIN COMPLEXES IN PLASMA AT 20-DEGREES-C AND AT 37-DEGREES-C

Small amounts of thrombin were added to human plasma containing 125I-fibrinogen to generate fibrin. Thereafter, thrombin was quenched with hirudin and 131I-fibrinogen added for internal calibration. Gel filtration of this mixture on sepharose CL-6B columns equilibrated with plasma revealed two peaks, one (peak A) eluting with the void volume, the other (peak B) with the volume corresponding to the fibrinogen peak. At 20°C, a small amount of 131I-fibrinogen (4.5%) was eluted together with the thrombin-treated 125I-fibrinogen in peak A, whereas at 37°C, no 131I-fibrinogen was recovered in peak A. If isolated fractions of peak A eluted at 20°C were rechromatographed at 20°C, they were eluted again in the void volume. At 37°C, however, this material was mainly eluted in peak B corresponding to the fibrinogen peak. If isolated fractions of peak B at 37°C were rechromatographed at 37°C, they were eluted with the same volume as in the original chromatography. At 20°C, however, the material was eluted in peak A as well as in peak B. These data show that at 20°C fibrin aggregates generated in a plasma medium from monomeric fibrin without incorporating fibrinogen. From these experiments, we conclude that so-called fibrin-fibrinogen complexes not stabilized by factor XIIIa generate only in vitro at 20°C, but do not exist at 37°C. © 1979.