The British Comparative Thromboplastin: the relationship between lipid class composition and procoagulant activity

Twenty-eight consecutive batches of the reference reagent British Comparative Thromboplastin (BCT) were produced in the National (UK) Reference Laboratory for Anticoagulant Reagents and Control (NRLARC) between 1969 and 1977. The relationship between procoagulant activity and lipid class composition in these batches at various stages of age deterioration on storage has been studied by a modification of the method of high pressure chromatography which allows better definition of the individual lipids. The free fatty acid concentration rose markedly while cconcentrations of phosphatidyl choline, phosphatidyl ethanolamine and phosphatidyl serine were reduced. An oxidative process is suggested and supported by the increase in malonaldehyde levels. The method of production of the BCT involves maceration of human brain which causes the breakdown of cell membranes and the release of many potentially oxidative materials from subcellular particles. The loss of procoagulant activity of BCT on storage may be due to the loss of phospholipid or to the increase of inhibitory degradation products, i.e. free fatty acid and malonaldehyde. The examination of the lipid class composition of tissue thromboplastin extracts appears useful, therefore, not only in determining the phospholipids necessary for procoagulant activity, but also in monitoring the deterioration of tissue thromboplastins on storage.