The Antigenic Properties of Fibrinogens

Abstract Previous publications (1) (2) from this laboratory have pointed out the inadequacy of the usual methods of blood defibrination in preparing fibrinogen-free serum and particular methods have been given by which such a serum may be obtained. The fact has also been established that traces of fibrinogen in a serum profoundly modify the immune reactions of that serum both in vivo and in vitro, provoking shock reactions in the former and pseudoprecipitin and agglutinin reactions in the latter. Continuing the study of fibrinogen in relation to immune reactions we have recently tested the antigenic properties of fibrinogen and this paper presents evidence that the injection of foreign fibrinogen into an animal induces the production of antibodies specific for the particular fibrinogen used. The fibrinogen chiefly employed in our experiments was prepared from well developed Plymouth Rock cockerels. From each of a group of birds approximately 20 co. of blood were drawn into glass tubes containing 0.2 cc. of a 50 per cent solution of sodium citrate. The blood from the several tubes was pooled at once and thoroughly centrifugalized. The supernatant plasma was removed and for each 100 cc. of plasma, 24 grams of sodium chloride (C.P.) were added, the addition being accompanied by vigorous shaking. The plasma was then placed at +6°C. for fifteen minutes. The resulting fibrinogen precipitate was recovered by centrifugalization and redissolved in distilled water. Multiple reprecipitations with sodium chloride were made and the final fibrinogen product was dissolved in an amount of distilled water equal to the original volume of plasma. All terms of dilution used in the protocols are relative to this “Standard” solution. The fibrinogen prepared from sheep and horse bloods and used in cross titrations was obtained in the same manner except that 30 grams of sodium chloride were added per 100 cc. of plasma to effect fibrinogen precipitation.