The Clot-Promoting Effect of Soaps of Long-Chain Saturated Fatty Acids*

Soaps of long-chain saturated fatty acids are said to accelerate the coagulation of mammalian plasma (1)(2)(3)(4)(5)(6).Concentrations of soaps compara- ble to the concentration of free fatty acids found in human plasma shorten the recalcified clotting time and accelerate the formation of artificial thrombi in vitro (5, 6).Whether the free fatty acids normally present in human plasma serve a physiologic function in hemostasis is yet to be determined.The mechanisms through which soaps of fatty acids promote clotting have not yet been clarified.Connor (6) proposed that soaps act to initiate clotting, behaving in a manner analogous to glass.Thus he believes that soaps, like glass, activate Hageman factor, an agent present in mammalian plasma.The experiments to be reported here do not support this view.They imply, on the con- trary, that soaps probably act in a unique way by accelerating the formation of activated plasma thromboplastin antecedent (activated PTA) from its precursor, plasma thromboplastin antecedent (PTA), whether by activated Hageman factor or "spontaneously."Although the concentrations of free fatty acids in plasma may be abnormally high under conditions in which intravascular thrombosis is likely to occur (7, 8), the studies to be de- scribed do not provide evidence for a causal re- lationship. METHODSAll studies were performed with blood, plasma, or plasma fractions that had been collected or prepared in silicone-coated tubes.Unless otherwise noted, direct contact with glass or similar clot-promoting substances was avoided.