The anticoagulant effects of the hookworm, ancylostoma ceylanicum: observations on human and dog blood in vitro and infected dogs in vivo.

Extracts of adult Ancylostoma ceylanicum prolonged the prothrombin time (PT) and partial thromboplastin time with kaolin ( PPTK ) of both human and dog plasmas in vitro. Excretory/secretory (E/S) products of these worms had similar effects while larval extract prolonged the PTTK only. Thus, the anticoagulant activities of this parasite are dependent upon the stage of the worm's life cycle. Collagen- and ADP-induced platelet aggregation were inhibited by adult and larval extracts. When the peripheral blood and bleeding times of dogs with varying worm burdens were examined, the only abnormality was shortening of the PTTK in the most heavily infected animals. Homogenates of dog small bowel subjacent to adult hookworms prolonged the PT of dog plasma and electron microscopical examination of this tissue revealed aggregation of platelets in blood venules without fibrin deposition. Thus, this study provides evidence that the anticoagulant properties of hookworms may have biological significance in infected animals.

Purification of an anticoagulant from the body fluid of Ascaris suum.

An anticoagulant has been purified from the body fluid of Ascaris suum by sequential passage through Sephadex G-50, CM-cellulose and Sephadex G-25 columns then treated with 2 M NaCl, passaged through a Sephadex G-25 column, separated from the phosphate buffer by precipitation of the latter with the CaCl2, then passaged through a Sephadex G-10 column in water. In the body fluid of the worm, the anticoagulant is ionically-bound to a carrier substance. The complex can be split by treatment with 2 M NaCl. The molecular weight of the anticoagulant is slightly less than 1400.

Inhibition of human blood clotting by extracts of Ascaris suum.

The effects of soluble extracts of Ascaris suum on human blood coagulation were investigated. Whole worm supernatant solution prolonged the whole blood clotting time and the kaolin-activated, partial thromboplastin time but it did not alter the prothrombin time. These data indicate impairment of the intrinsic pathway of blood coagulation. Whole worm supernate inhibited platelet aggregation induced by ADP and ristocetin. This supernate did not affect fibrinolysis. The maximal concentration of anticoagulant activity was found in the pseudocoelomic fluid of the worm. Activity was also noted in the cuticle and secretory/excretory products. Perhaps inhibition of blood clotting by helminths may facilitate their passage through the blood stream.