Preparation of antihemophilic factor from indated plasma

Four large-scale batches of Antihemophilic Factor (AHF, factor VIII) were prepared from plasma derived from 4 to 6-day-old blood applying a method developed for preparation of AHF from fresh frozen plasma. The AHF product was 6 to 9-fold concentrated over plasma with 7 to 10-fold purification and a recovery of 100 to 140 factor VIII units per liter of starting plasma. In terms of purity and yield, this is about half that of AHF obtained from fresh frozen plasma. The AHF concentrate was free of detectable thrombin and plasmin and the solubility of the dry product was comparable to that of the product derived from fresh plasma but the hemoglobin content was slightly increased. After further fractionation with polyethylene glycol (PEG 4000), a highly soluble AHF product 100-fold purified, and 30-fold concentrated, was obtained with 60% factor VIII recovery, which corresponds to a final yield of 60 to 85 factor VIII units per liter of starting plasma.     

Preparation of antihemophilic factor and fibronectin from human plasma cryoprecipitate

Starting with human plasma cryoprecipitate, fibronectin was separated from antihemophilic factor (AHF) by fractional precipitation under mild conditions resulting in excellent recovery of AHF in the supernatant solution of the cryoprecipitate. Separation of fibronectin enabled accelerated sterile filtration of the supernatant solution containing AHF even after three- to fourfold concentration (by ultrafiltration) to desired potency. The sterile AHF concentrate, dispensed at 1000 u per vial and lyophilized, was completely dissolved within 3 minutes upon addition of 30 ml of pure water. The expected increment in circulating factor VIII and its hemostatic effects were found following intravenous infusion into factor VIII-deficient patients. Yield of AHF of five successive batches, each starting with the cryoprecipitate from some 12,000 units of fresh-frozen plasma, averaged 51 percent. The fibronectin precipitate was purified by affinity on insolubilized gelatin with chaotropic elution at pH 5.5 followed by removal of the chaotrope by diafiltration. Thermal denaturation of adventitious fibrinogen resulted in electrophoretically pure fibronectin which, following lyophilization and reconstitution with pure water, retained biological properties in an in vitro assay designed to reflect opsonic activity. The yield of fibronectin for seven successive batches, each starting with the cryoprecipitate from some 900 units of fresh-frozen plasma, averaged 10 percent.     

Defective Ristocetin-Induced Platelet Aggregation in von Willebrand''s Disease and its Correction by Factor VIII

The antibiotic ristocetin, in concentrations of 1.0-1.5 mg/ml, aggregated normal platelets in citrated platelet-rich plasma by a mechanism in which the release reaction played only a minor role. Platelet aggregation by ristocetin in a concentration of 1.2 mg/ml was absent or markedly decreased in 10 patients with von Willebrand's disease. Lesser degrees of abnormality were obtained with a concentration of 1.5 mg/ml. The magnitude of the defect in ristocetin-induced platelet aggregation correlated well with the degree of abnormality of the bleeding time and the levels of antihemophilic factor (AHF, VIII(AHF)) procoagulant activity. In all patients, the defect in ristocetin-induced platelet aggregation was corrected in vitro by normal plasma. Correction was also obtained with a fraction of normal cryoprecipitate that eluted in the void volume with VIII(AHF) after chromatography on a gel that excludes molecules larger than 5 x 10(6). A similar fraction, devoid of VIII(AHF) activity, obtained from patients with von Willebrand's disease had no corrective effect, but fractions obtained from patients with hemophilia were just as effective as those obtained from normal subjects. The correction activity of plasma and partially purified factor VIII was inhibited by a rabbit antibody to human factor VIII but not by a human antibody against VIII(AHF) procoagulant activity. The studies provide further evidence that patients with von Willebrand's disease are deficient in a plasma factor that is necessary for normal platelet function. The activity of this factor appears to be associated with factor VIII but is unrelated to VIII(AHF) procoagulant activity.     

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 Pool's 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.     

A novel, automated method of temperature cycling to produce cryoprecipitate

BACKGROUND: Cryoprecipitate continues to find wide application in transfusion practice. Current AABB standards call for a minimum of 80 units (U) of factor VIII and 150 mg of fibrinogen per bag of cryoprecipitate. However, individual cryoprecipitates can vary greatly in content, with as many as 20 different factors known to affect the yield. STUDY DESIGN AND METHODS: Plasma was processed in a new, rapid, automated device (CryoSeal, Thermogenesis) with computer-controlled temperature cycling to produce cryoprecipitate. RESULTS: In repeat runs (n = 20), the automated procedure yielded a product containing 184 mg of fibrinogen and 158 U of factor VIII in 55 minutes. Additional studies using plasma pools to compare the quality of the machine-generated products to those of traditionally prepared cryoprecipitate showed comparative recoveries of 182 and 187 mg of fibrinogen and 172.1 and 129.7 U of factor VIII and no significant difference in the levels of plasminogen, protein C, or protein S. CONCLUSION: The new system offers an automated method of cryoprecipitate production in which the steps involved in temperature cycling are initiated sequentially, producing within 1 hour a preparation that is equivalent to standard cryoprecipitate.     

Effects of triiodothyronine-induced hypermetabolism on factor 8 and fibrinogen in man

Triiodothyronine (liothyronine sodium) (400-500 mug/day for 14 days) was given to six normal subjects. Factor VIII (antihemophilic globulin) activity increased from 109 to 167% (P < 0.05); fibrinogen increased from 344 to 581 mg/100 ml (P < 0.01). To test whether the increases in factor VIII activity and fibrinogen were mediated by beta adrenergic receptors, propranolol (20 mg every 6 hr) was given orally to four other normal subjects in addition to triiodothyronine for 14 days. Factor VIII increased from 100 to 161%; fibrinogen increased from 374 to 564% (P < 0.01). Factor VIII activity did not change in a severe classical hemophiliac made hypermetabolic with triiodothyronine, but it increased from 39 to 82% in a patient with von Willebrand's disease. Triiodothyronine-induced hypermetabolism increased the incorporation of selenomethionine-(75)Se into plasma fibrinogen. These results suggest that the increases in clotting factor activity during triiodothyronine-induced hypermetabolism reflect an effect of increased protein synthesis rather than enhanced stimulation of beta adrenergic receptors.     

去冷沉淀血浆与普通血浆临床应用价值的比较

目的探讨去冷沉淀血浆中部分有效成分的实际含量,为临床选择不同血浆输注提供实验室依据。方法采集23袋（200ml/袋）ACD-B血液保存液保存的血液,4h内分离制备新鲜冰冻血浆,各袋均留2份标本;1份同新鲜冰冻血浆一起置-35℃保存,于第3天速融后检测总蛋白、白蛋白、纤维蛋白原、凝血因子Ⅴ、Ⅷ、Ⅹ含量;1份置4℃保存21d后检测总蛋白、白蛋白、纤维蛋白原、凝血因子Ⅴ、Ⅷ、Ⅹ含量;新鲜冰冻血浆于第3天取出制备冷沉淀,留取去冷沉淀血浆标本1份检测总蛋白、白蛋白、纤维蛋白原、凝血因子Ⅴ、Ⅷ、Ⅹ含量。结果去冷沉淀血浆中的血浆蛋白和凝血因子均低于普通血浆（P〈0.001）。结论去冷沉淀血浆的使用价值有局限性,不能与普通血浆等同使用。     

The inactivation of hemostatic factors by hematin

Prolonged clotting times and reduced levels of clotting factors have been reported in hematin-treated patients. This effect persists for up to 5 hr after hematin infusion, associated with plasma levels ranging from 0.01 to 0.04 mg/ml. Therefore we performed in vitro studies to investigate the effects of hematin on fibrinogen, thrombin, factor VIII:C, and plasmin. Hematin in a final concentration of 0.01 mg/ml inhibited the clotting of bovine fibrinogen (1.3 to 2.6 mg/ml) by bovine thrombin (0.12 U/ml) and inhibited the hydrolysis of a synthetic substrate by human thrombin. However, if the hematin was first mixed with albumin (25 mg/ml), fourfold higher concentrations were required to prolong the thrombin clotting time. Hematin, 0.035 mg/ml, reduced VIII:C activity from 0.88 to 0.40 U/ml as measured by two-stage assay. Hematin (0.05 mg/ml) also inhibited the activation of VIII:C by thrombin (0.04 U/ml): baseline activity, 0.84 U/ml; thrombin-activated, 2.94 U/ml; with hematin added, 1.33 U/ml. Hematin also inhibited clot lysis. The inclusion of hematin (0.03 mg/ml) in the diluting buffer reduced the lysis of whole blood clots from 86% +/- 5 to 23% +/- 5 (p less than 0.001, mean +/- S.D. of four determinations) and decreased the lysis of 125I-fibrin clots induced by plasmin (0.02 CTA U/ml) from 100% to 27%. In concentrations as low as 0.09 microgram/ml, hematin inhibited the hydrolysis of a synthetic substrate by plasmin. Hematin was mixed with fibrinogen, albumin, or thrombin, and the mixtures applied to Sephadex G-200 columns. Adherence of the hematin to Sephadex was prevented by either prerinsing the column with albumin or using borate buffer at pH 9.2. Hematin co-eluted with each protein applied to the column and, in the case of fibrinogen, altered its electrophoretic mobility and markedly prolonged the thrombin clotting time of the eluted fibrinogen. We conclude that hematin binds to a variety of hemostatic proteins, inhibiting their biologic activity.     

Stabilization of Factor VIII in Plasma by the von Willebrand Factor: STUDIES ON POSTTRANSFUSION AND DISSOCIATED FACTOR VIII AND IN PATIENTS WITH VON WILLEBRAND''S DISEASE

In normal plasma, the ratio of the procoagulant activity of factor VIII (VIII(AHF)) to that of the von Willebrand factor activity (ristocetin cofactor, VIII(VWF)) or factor VIII antigen (VIII(AGN)) is approximately 1, but ratios > 1 (e.g., VIII(AHF) > VIII(VWF) or VIII(AGN)) may be observed in some patients with von Willebrand's disease and in the "late" posttransfusion plasmas of patients with this disorder. The lability of VIII(AHF) was studied by incubating plasma, diluted 1:10 in imidazole buffer pH 7.1, for 6 h at 37 degrees C. With normal plasmas, 77+/-12% (SD) of the original VIII(AHF) activity remained after incubation. VIII(AHF) was labile (e.g., 35-55% residual activity) in the "late" posttransfusion plasmas (VIII(AHF) > VIII(VWF)) of a patient with von Willebrand's disease, but not in the "early" posttransfusion plasmas (VIII(AHF) approximately VIII(VWF)). VIII(AHF) was also labile in the (base-line) plasmas of three patients with von Willebrand's disease in whom the ratios of VIII(AHF) to VIII(VWF) were 4.4 to 8.1, but not in the plasmas of four other patients in whom the ratio was approximately 1. The electrophoretic mobility of factor VIII antigen was increased in two of the three patients with labile VIII(AHF). In both of these patients, and in the late posttransfusion plasmas, labile VIII(AHF) activity could be stabilized by the addition of purified von Willebrand factor (lacking VIII(AHF) activity) or by hemophilic plasma, but not by plasmas of patients with severe von Willebrand's disease. Thus, VIII(VWF) may serve to stabilize VIII(AHF) and this might explain the posttransfusion findings in von Willebrand's disease.     

Determinants of factor VIII recovery in cryoprecipitate

Many aspects of the production of cryoprecipitate were studied to determine which methods resulted in the greatest recovery of Factor VIII. The following recommendations resulted: 1) blood should be mixed with anticoagulant throughout phlebotomy; 2) blood should be centrifuged within a few hours of collection; 3) larger satellite bags should be used to contain the usual volume of plasma, for example, 200 ml of plasma should be frozen in a 600-ml capacity bag; 4) plasma should be centrifuged as soon as thawing is complete; 5) cryoprecipitate should be refrozen on dry ice; 6) cryoprecipitate should be stored at or below -30 C.; and 7) prolonged storage of frozen plasma or cryoprecipitate should be avoided. Variations in Factor VIII content from one bag of cryoprecipitate to another, under uniform production conditions, depends largely on two donor-specific attributes which tend to remain constant from time to time, namely, the donor's plasma Factor VIII level and the cryoprecipitability of his Factor VIII.     

Evaluation of factor VIII-rich cryoprecipitate and the plasma fibronectin-rich, heparin-precipitable fraction prepared from single- donor plasma units

A plasma fibronectin-rich component was prepared by heparin-induced 4 degrees C precipitation of fresh or stored (21 days at 4 degrees C), single-donor plasma. The recovery of plasma fibronectin was 45 percent at a concentration of 0.05 mg heparin per ml (7.5 units/ml) and 75 percent at 0.1 mg per ml (15 units/ml). The biologic activity of plasma fibronectin, as assessed by the spreading of Chinese hamster ovary cells or attachment of monocytes to gelatin-coated surfaces, was similar to that of plasma fibronectin concentrates made from fresh or stored plasma. Only 20 to 30 percent of the factor VIII activity in fresh plasma was recovered in cryoprecipitate produced after the heparin-induced precipitate containing fibronectin was removed. Cryoprecipitate prepared from the supernatant plasma that remains after heparin-induced cold precipitation in the presence of CaCl2 (5 mM) contained approximately 50 percent less factor VIII. The relatively low recovery of factor VIII in cryoprecipitate prepared from fibronectin-depleted plasma makes cryoprecipitation an unsuitable method of producing fibronectin-rich and factor VIII-rich components effectively from a single unit of fresh plasma. However, heparin-induced cold precipitation provides an efficient method for preparing plasma fibronectin concentrates from small plasma pools or single units of stored or fresh plasma.     

Postthaw stability of fibrinogen in cryoprecipitate stored between 1 and 6 degrees C

The fibrinogen activity in thawed cryoprecipitate stored between 1 and 6 degrees C is maintained essentially unchanged in most bags for a month. Occasionally, a bag will have a reduction in fibrinogen. If pooling has not occurred, thawed cryoprecipitate should be useful as a source of fibrinogen for a period of time considerably in excess of the 6 hours allowed for its use as a source of factor VIII or von Willebrand factor.     

Quantitative Assay of a Plasma Factor Deficient in von Willebrand''s Disease that is Necessary for Platelet Aggregation. RELATIONSHIP TO FACTOR VIII PROCOAGULANT ACTIVITY AND ANTIGEN CONTENT

In a previous paper, we showed that the abnormality of ristocetin-induced platelet aggregation in platelet-rich plasma in 10 patients with von Willebrand's disease could be corrected by a factor in normal plasma that was present in the same fractions as factor VIII procoagulant activity (antihemophilic factor, AHF, VIII(AHF)) when prepared by chromatography on Bio-Gel 5 M (Bio-Rad Laboratories, Richmond, Calif.). This observation suggests that patients with this disorder are deficient in a plasma factor, associated with the factor VIII molecule, that is necessary for normal platelet function. In the present paper, we describe, an assay for this factor, the von Willebrand factor (VIII(VWF)), based on the observation that a log-log relationship exists between the amount of ristocetin-induced aggregation of washed, normal platelets and the concentration of normal plasma present in the test system. We assayed the activity of VIII(VWF) as well as antihemophilic factor procoagulant activity (VIII(AHF)) and factor VIII antigen (VIII(AGN)) in 15 patients with von Willebrand's disease and 20 normal subjects. A highly significant correlation (r approximately 0.80) between VIII(VWF) and both VIII(AHF) was found in normal subjects and in patients with von Willebrand's disease. This finding, in addition to the observation that agarose gel chromatography fractions that have VIII(AHF) procoagulant activity also have VIII(VWF) activity, strongly suggests that the von Willebrand factor is associated with the factor VIII molecule. VIII(VWF) in normal plasma was not inhibited by human anti-VIII, and VIII(VWF) levels were normal in hemophilic plasma. Thus, the VIII(VWF) site on the factor VIII molecule appears to be different from that determining VIII(AHF). Finally, the activity of VIII(VWF) appeared to correlate better with the bleeding time than either VIII(AHF) or VIII(AGN). This suggests that VIII(VWF) assayed in this study may be the "anti-bleeding factor" that is deficient in von Willebrand's disease. These findings are consistent with a decreased synthesis of the factor VIII molecule in von Willebrand's disease and suggest the possibility of additional abnormalities of the site on the molecule that determines the activity of VIII(VWF).     

Preparation of pooled cryoprecipitate for treatment of hemophilia A in a home care program

Cryoprecipitate is used infrequently in home therapy for patients with hemophilia A since freezer storage is required and resuspension and pooling of thawed cryoprecipitate is cumbersome. We evaluated procedures for preparation of cryoprecipitate in an "open system" so that four to six bags of cryoprecipitate could be pooled after production and refrozen for home therapy. Factor VIII activity for pooled cryoprecipitate was 132 +/- 30 (mean +/- SD), 125 +/- 45, and 145 +/- 47 units per bag pooled in three separate studies. Cultures from cryoprecipitate pools and individual cryoprecipitate bags did not show contamination in the "open system" or with the water bath thawing procedure. The mean increment in factor VIII activity per unit per kg infused was 0.02 units per ml and the mean half-life was 10.5 hours in three patients with hemophilia A. Pooled cryoprecipitate was shown to be clinically efficacious and acceptable for use in home care programs for hemophilia A.     

Comparison of coagulation factor XIII content and concentration in cryoprecipitate and fresh-frozen plasma

BACKGROUND: For patients with plasma coagulation factor XIII (pFXIII) deficiency, recommended means of replacement include infusions of fresh‐frozen plasma (FFP), cryoprecipitate, or (where available) factor (F)XIII concentrates. Quantitative differences in pFXIII concentration in FFP and cryoprecipitate are not well defined and were, therefore, the subject of this study. STUDY DESIGN AND METHODS: FFP and cryoprecipitate (10 bags each from blood group O donors) were analyzed to quantify pFXIII activity and antigen. Coagulation FVIII, fibrinogen, and von Willebrand factor (VWF) were also quantitated. RESULTS: Mean (±SD) pFXIII activity in cryoprecipitate and FFP bags was 60 ± 30 and 288 ± 77 U per bag, respectively, and pFXIII antigen and activity levels were concordant. Other comparisons (mean ± SD) between cryoprecipitate and FFP, respectively, were as follows: coagulation FVIII activity, 133 ± 37 and 265 ± 83 U per bag; fibrinogen content (Clauss kinetic assay), 183 ± 44 and 725 ± 199 mg per bag; VWF antigen content, 181 ± 53 and 218 ± 70 U per bag; VWF ristocetin cofactor activity, 168 ± 34 and 221 ± 65 U per bag; VWF collagen‐binding activity, 164 ± 40 and 208 ± 71 U per bag; and fluid (plasma) volumes per bag, 21.3 ± 2.7 and 245 ± 29 mL. CONCLUSION: In contrast to other cryoprecipitable coagulation proteins, pFXIII is only mildly enriched in cryoprecipitate when compared with FFP (approx. two‐ to threefold). Although both products can provide effective pFXIII replacement, FFP may be preferred when infusion volume is not a major consideration and pFXIII concentrates are not available. VWF is substantially enriched in cryoprecipitate (approx. ninefold compared with its concentration in FFP), with VWF activity content exceeding that of FVIII by approximately 26 percent on average.     

Immunofluorescent Localization of Antihemophilic Factor Antigen and Fibrinogen in Human Renal Diseases

Tissue localization of antihemophilic factor (AHF, factor VIII) antigen and fibrinogen by immunofluorescent microscopy was determined in 146 specimens of normal and diseased kidneys. AHF antigen was present in the endothelial cells of glomeruli, peritubular capillaries, arteries, and veins of normal kidneys; a distribution similar to that in other tissues. In scleroderma and malignant hypertension, deposition of AHF antigen and fibrinogen was limited to the markedly thickened endothelial layers of arteries. More extensive intense deposition of both AHF antigen and fibrinogen in glomeruli and in arterial walls were present in hyperacute renal homograft rejection, hemolyticuremic syndrome, postpartum renal failure, and in some cases of acute homograft rejection. In contrast, deposition of fibrinogen was observed in glomerular epithelial cresents in severe proliferative glomerulonephritis, but AHF deposition was not present in these lesions. Glomerular deposition of fibrinogen without increased AHF standing was also detected in renal tissue from patients with anaphylactoid purpura nephritis and in recurrent macroscopic hematuria with focal glomerulonephritis. Increased staining of peritubular capillaries with anti-AHF was seen in diseased kidneys irrespective of etiology. Immunofluorescent localization of AHF, a participant in the intrinsic coagulation pathway, offers a new way by which to analyze the mechanisms responsible for fibrinogen deposition in disease.     

Cryoprecipitate prepared from plasma treated with methylene blue plus light: increasing the fibrinogen concentration

When cryoprecipitate is prepared from plasma which has been treated with methylene blue plus light (MB) for the purpose of virus inactivation, clottable fibrinogen content is 40% lower compared with units prepared from untreated plasma. Initial studies showed that when frozen MB plasma units were removed to +2 to +6 degrees C for 4 h and then returned to -40 degrees C prior to cryoprecipitation, fibrinogen recoveries increased from 24 to 42%. Although fibrinogen yield improved when plasma units were stored at +2 to +6 degrees C for varying lengths of time, FVIII levels decreased with increasing time. Conditioning for 8 h was studied in more detail. Groups of two plasma units were mixed together, divided into two equal units, frozen/thawed and treated with MB. One of each pair was stored continually at -40 degrees C, whereas the other was removed to +2 to +6 degrees C for 8 h. Samples were assayed for fibrinogen, FVIII, VWF:Ristocetin cofactor activity (RCo), VWF:Ag and VWF:Collagen binding (CB). The cryoprecipitate fibrinogen content increased to a mean of 207 mg unit(-1). VWF:Ag, VWF:RCo and VWF:CB recoveries also increased. FVIII recovery decreased from 50 to 45% (mean 124 iu unit(-1)). Conditioning has been validated for routine production of cryoprecipitate from imported plasma.     

Preparation of cryoprecipitated factor VIII concentrates

Factors affecting the yield of factor VIII in cryoprecipitate have been investigated in the context of a blood component program. Both in vitro and in vivo measurements were used to assess the effects of critical variables on the yield of factor VIII activity. Variables such as anticoagulant, plastic bag, mixing during collection, and platelet contamination had no significant effect on yield of factor VIII activity in cryoprecipitate. Among the most critical factors affecting yield were storage time of whole blood and procedures for freezing, thawing, and reconstitution. The following procedures were found to assure a 60 per cent recovery of factor VIII in cryoprecipitate: 1)processing of whole blood within six hours of collection; 2)use of a technique to freeze plasma within 30 minutes either in a −70 C ethanol bath or −85 C freezer; 3)rapid thawing (1 1/2 hour or less) in a 4 C circulating water bath; 4)centrifugation at 4,500 × g for 10 minutes at 4 C followed by draining of the supernatant in a 4 C cold room; 5) storage of the precipitate at −20 C until ready for use; 6) thawing in a 37 C water bath for at least 15 minutes followed by addition of 20 ml of 0.15 M saline for a 20 minute period at room temperature, and gentle mixing before pooling units for transfusion. The recovery of factor VIII in cryoprecipitate appears to be limited to about 65 per cent by its solubility in plasma at 4 C. Therefore, further effort to increase the amount available for treatment should involve improving the supply of plasma for its preparation and decreasing the cost of processing.     

A comparison of factor VIII activity in cryoprecipitates prepared from ACD and CPD plasma

In an attempt to develop a method to produce a cryoprecipitate with a predictable Factor VIII potency, several variables were studied and statistically analyzed. These included the hematocrit, age, blood group and Rh type of the donor; possible epinephrine release; the degree of lipemia, volume, pH and Factor VIII activity of the donor plasma; the volume of cryoprecipitates, its Factor VIII activity and the per cent yield; and the Factor VIII activity of the supernatant plasma. Cryoprecipitates were prepared by the method of Pool and Shannon from the plasmas of 40 random male donors, half the bloods being drawn in ACD and half in CPD. None of the variables had a significant influence on the per cent yield of activity, although the mean values obtained suggest that the per cent yield of Factor VIII activity in the cryoprecipitates prepared from CPD plasmas is higher than in those prepared from ACD plasma. Although the per cent yield of Factor VIII in cryoprecipitates prepared from CPD plasma is not significantly different from that of ACD plasma, the mean total units of Factor VIII activity is significantly higher in CPD cryoprecipitates. It also was confirmed that a higher per cent Factor VIII activity in the donor results in a relatively higher activity in the cryoprecipitate. The data indicate that if CPD plasma collected from donors having above a certain minimum per cent activity were used for cryoprecipitate production, one could be assured of having a minimum of 100 units of Factor VIII activity per bag.     

Modulation of fibrinogen content in cryoprecipitate by temperature manipulation during plasma processing

In routine blood bank production of single-donation cryoprecipitate, the introduction of a 16-hour hold at 4 degrees C, with the frozen plasma units packed into polystyrene containers, resulted in plasma prethaw temperatures of -4 degrees C to -8 degrees C. This in turn resulted in cryoprecipitate fibrinogen levels that were 214 percent of those obtained when units were thawed immediately after removal from -30 degrees C storage. In scale-model production of factor VIII concentrate, plasma warmed from -30 to -10 to -15 degrees C over 18 hours before pooling and thawing yielded cryoprecipitate fibrinogen levels that were 66 percent of those found in plasma warmed to -2 to -5 degrees C over the same period. Processing -30 degrees C plasma without a warming period led to cryoprecipitate fibrinogen levels that were 40 percent of those obtained from plasma warmed to -2 to -5 degrees C. These differences were accentuated after purification of the cryoprecipitates to an intermediate-purity factor VIII concentrate. These results suggest that simple modifications in production methods allow the fibrinogen content of cryoprecipitate to be tailored to specific uses.