Utilization of the Labile Factor During Normal and Abnormal Coagulation of Blood.

Abstract

Percentages of prothrombin, labile factor and accelerator effect were determined after coagulation of blood in sera of healthy subjects and patients with different pathological conditions. The 3 factors were detd. by the method of Quick (Jour. Lab. and Clin. Med. 34: 761. 1949 ), Stefanini (Amer. Jour. Clin. Path. 20: 233. 1950 ) and de Vries et al. (Blood 4: 247. 1949 ), respectively. The percentages of labile factor and prothrombin activities and accelerator effect found in serum after completion of the coagulation of blood were found to be in inverse quantitative proportions. A very small percentage of labile factor and prothrombin activity was found in sera of healthy subjects; in this case high values of the accelerator were the rule. Low values of accelerator and a large percentage of prothrombin and labile factor activity were found whenever the formation of thrombin was deficient because of the depletion of either thromboplastin (such as in hemophilia and thrombocyto-penic purpura) or prothrombin and labile factor (liver dysfunction). In dicumarol hypoprothrombinemia the available prothrombin was well utilized during coagulation, but the percentage in serum of unconverted labile factor was high and that of ac-celator low. These findings suggest that: (a) prothrombin, thromboplastin and labile factor react to form thrombin in definite quantitative relationship; and (b) the accelerator agent in serum is probably derived from the labile factor of plasma through the activating action of thrombin.