Granulocyte lysosomal cationic protein alters fibrin assembly: a possible mechanism for granulocyte control of clot structure.

The effect of highly positively charged molecules on the assembly and structure of thrombin-induced fibrin gels was studied with turbidity techniques. Lysosomal cationic proteins (LCP) extracted from rabbit heterophils produced enhanced lateral association of fibrin fibers. A crude extract of LCP had little effect on kinetics but produced an increase in the final fiber mass/length ratios. A purified fraction, LCP-5, of the crude extract enhanced both the initial rate of increase and final turbidity of fibrin gels. Mass/length ratios obtained for fibrin fibers as a function of LCP-5 concentration varied from 4.3 X 10(12) in the absence of LCP-5 to 7.8 X 10(12) daltons/cm at 1 microgram LCP-5/ml. Similar studies were conducted with protamine as the perturbant of fibrin assembly. Mass/length ratios were increased from 5.7 X 10(12) daltons/cm with no protamine to 8.5 X 10(12) daltons/cm at 100 micrograms protamine per milliliter. High concentrations of both LCP and protamine precipitated fibrinogen. This phenomenon may imply a mechanism by which the blood cellular components may modulate clot structure through the release of highly charged molecules such as LCP-5.