Platelet functions have been studied in relation to hemostasis in two patients with congenital afibrinogenemia.

Neither in the plasma nor in the aqueous platelet extracts of these patients was fibrinogen detectable by immunoelectrophoresis or with the aid of the Ouchterlony technique. ADP-induced platelet aggregation, adhesion to connective tissue particles, viscous metamorphosis under the influence of thrombin, clot retraction activity of the platelets, as well as their factor 3 activity were all found normal. Abnormal was the behaviour of the patient’s platelets on glass surfaces : they were unable to adhere to glass and the typical spreading on such surfaces was equally missing. This defect was normalized in vitro by the addition of small amounts of fibrinogen and correspondingly the patients platelets showed normal adhesiveness after fibrinogen transfusions. Normal platelets, suspended in afibrinogénémie plasma lost their adhesiveness toward glass surfaces.

After transfusion of Cohn fraction I the prolonged bleeding time of the patients was normal and the clinical improvement presisted for a period of about 3 weeks, this inspite of the fact, that no fibrinogen was detectable by the usual methods 10 days after the transfusion.

The significance of these results as well as their implications for the role of fibrinogen in hemostasis are discussed.