Robert D. Langdell

Antihemophilic Factor (AHF) Levels Following Transfusions of Blood, Plasma and Plasma Fractions.∗

Summary 1. Canine and human hemophilic subjects were transfused with homologous blood or plasma, Dogs were also transfused with AHF-rich plasma fractions. The increase in plasma AHF levels following transfusions was proportional to the amount of AHF administered. Over half of the AHF activity disappeared within a few hours, although traces of AHF may persist for nearly a week. Frequent replacement transfusions are required if AHF levels as high as 5-10% are to be maintained. 2. Injection of potent plasma fractions into normal dogs resulted in transient supernormal AHF levels. Half of the injected AHF was lost in about 2 hours. 3. The minimum amount of AHF required to give normal values is not uniform with different clotting tests. AHF levels above 1% resulted in normal values for the clotting time and prothrombin utilization tests. Levels above 15% resulted in normal values for the PTT test.

Prothrombin Utilization during Clotting Comparison of Results with the Two-Stage and One-Stage Methods.

Summary 1. A comparison was made of the changes in prothrombin during clotting, as indicated by the one- and 2-stage methods. 2. By the 2-stage method, progressive disappearance of prothrombin from serum was observed. Prothrombin utilization was slower in human blood than in dog blood, and was delayed greatly in canine hemophilic blood, platelet-poor human plasma, and in blood clotting in silicone-treated glassware. 3. By the one-stage method, an initial period of hypoactivity in the plasma was followed by a hyperactive phase in the serum. At the peak of hyperactivity, “prothrombin” values were about 180% of the control plasma. In slowly clotting bloods, the hyperactive phase developed less rapidly and persisted for a longer period than in normal blood. The abnormally high serum prothrombin values obtained by the one-stage test appear to be due to the evolution and persistence of the recently recognized serum factor which accelerates thrombin formation. Apparently this factor does not influence the 2-stage serum prothrombin values.

Histamine-Induced Increase in Fibrinolytic Activity.∗

Summary Intravenous injection of histamine phosphate in the dog in a dosage of 50-200 μg/kg body weight increased the fibrinolytic activity of the plasma and of the euglobulin fraction of the plasma. The plasma antiplasmin and protein content of the euglobulin fraction were not altered. The level of GOT in the plasma increased after injection of histamine but the rise appeared later than the rise in fibrinolytic activity.

Antihemophilic factor (AHF): plasma levels after administration of AHF preparations to hemophilic dogs.

Summary 1. The plasma tide of AHF was measured after subcutaneous and intramuscular injections of bovine AHF fractions into hemophilic dogs. Better results were obtained with intramuscular than with subcutaneous administration; higher plasma AHF levels were maintained for longer times. Citrate in adequate concentration in the AHF solutions appeared to have an adjuvant action. 2. The rate of fall off of plasma AHF was followed after moderate levels of this clotting factor had been maintained for several hours. It is suggested that the biologic half-life of AHF in the dog may be at least 23 hours.

Clotting Factor Activity in Cryoprecipitates and Supernatant Plasma Prepared from Blood Collected into ACD, ACD-Adenine, CPD, and CPD-Adenine and from Plasma Collected by Plasmapheresis

Adenine has been used to prolong the survival of stored erythrocytes, and thus extend the storage period of blood. It seemed desirable to investigate the effect of this additive on the procoagulants of plasma that full use of cryoprecipitates and other plasma fractions could be made from blood drawn into an adenine‐enriched anticoagulant. Eight units of whole blood were drawn into each of four anticoagulants: ACD, ACD‐adenine, CPD, and CPD‐adenine. Cryoprecipitates were prepared from each unit of fresh plasma according to a modification of Pools method. Assays for fibrinogen, prothrombin, and factors V, VII, VIII, IX, and X were performed on the cryoprecipitates and on the supernatant plasma drawn off the cryoprecipitates. Adenine did not alter the expected yield of factor VIII (AHF) in the cryoprecipitate. There was slight to moderate loss of factor V and fibrinogen, respectively, in the supernatant plasma, but prothrombin and factors VII, IX, and X were unaffected by the procedure. Assays also revealed good AHF activity in each unit of plasma from a double plasmapheresis; therefore, both units are satisfactory for use in preparing cryoprecipitates.

Coagulation of Catfish Blood

Summary The blood of the fresh water catfish (Ameiurus nebulosus) clots rapidly. There appears to be species specificity of the prothrombin-thromboplastin reaction with both the one- and two-stage methods. Catfish brain thromboplastin causes rapid clotting of catfish plasma, but acts as a partial thromboplastin with canine plasma. Catfish plasma does not correct the long partial thromboplastin time of human plasmas deficient in factor V, factor VIII, factor IX, factor X, or factor XII.

Concentrated Antihemophilic Factor (AHF) from Outdated Blood

The antihemophilic factor (AHF) content of bank blood decreases during storage under standard blood bank conditions. In the present study, an average of 58 per cent of the original activity was present after the usual shelf life of 21 days expired. This material was concentrated by a modification of the Pool cryoprecipitation method. Almost 60 per cent of the residual AHF in the outdated plasma was found in the precipitate. The resulting precipitate was resuspended in about 25 ml of the residual plasma. On a volume basis, this had an average of about four times the activity of fresh human plasma. The cold insoluble material resuspended in residual plasma can be used for therapy without further processing. Following intravenous injection into hemophilic patients, high levels of circulating AHF, in excess of 60 per cent of normal, have been achieved without causing circulatory overload.

Antihemophilic Factor (AHF) Stability in Fresh Frozen Blood Bank Plasma

One hundred randomly chosen units of fresh frozen blood bank plasma were assayed for antihemophilic activity (AHF). A wide range in AHF levels was observed. The variability appears to be due in part to different AHF levels of donors. Most of the units had as much as 30 per cent less AHF than was contained in unfrozen, freshly prepared plasma. There was no trend toward lower values in plasma frozen up to 15 weeks. Many factors contribute to the unpredictable loss of AHF. The effects of slow and rapid freezing on the AHF content of plasma were studied. Freezing of fresh bank plasma in a bath of liquid and in air are compared. Plasma freezes much more rapidly in liquid, with negligible loss of AHF. Freezing is considerably slower in air, and losses of 20 per cent or greater frequently occur.

Serum Accelerator Factors and Antihemophilic Factor (AHF) in Early Phases of Clotting.

Summary 1. An eluate from BaSO4-ad-sorption of normal serum is shown to have a marked effect on the clotting time in hemophilia without altering the defect in prothrombin utilization. 2. The eluate is shown to operate chiefly by reducing the latent period of prothrombin utilization. 3. The effect of this eluate on AHF assays is discussed. 4. The necessity of platelets for prothrombin conversion is demonstrated again under different experimental conditions. 5. AHF is shown to be required for the demonstration of maximal prothrombic activity in the prothrombin time test.