Turbidimetric evaluation of the impact of albumin on the structure of thrombin-mediated fibrin gelation.

Recent studies have reported an interaction of albumin with polymerizing fibrin, resulting in a narrowing of gel fibers. It has been postulated that albumin interacts with the E domain resulting in delayed and thus altered polymerization. Utilizing turbidity techniques, the impact of human albumin on gels of human fibrin, clotted with human thrombin, was studied. The addition of albumin, at concentrations from 3 to 30 microM, to 1 mg/ml fibrin gels produced less than a 10% change in either the kinetics of turbidity increase or the subsequent fiber mass-length ratio. For a given calcium concentration, saturation of albumin's calcium-binding capacity by prior dialysis ablated even these small effects. Given these findings, it seems unlikely that albumin imposes a physiologically significant influence on fibrin polymerization. Structural changes secondary to albumin-mediated enhancement of factor XIII activity remain a possibility.