Abstract. A quantitative analysis was performed of the method of plasma fractionation used in our institute, a modified Cohn VI system, in order to develop and evaluate methods for the increment of antibody yield and quality of the immunoglobulin concentrate. For this purpose the distribution of the immunoglobulins IgG, IgM, IgA, the subclasses of IgG and several specific antibodies in the different fractions was analysed. In addition, the distribution of some plasma proteins which may be of importance for the quality of the immunoglobulin concentrate, such as α2M, α1‐antitrypsin, α2‐lipoprotein and fibrinogen, was determined. The average yield of IgG of immunoglobulin concentrates prepared from 31 plasma batches was 58% (SD 9%). Loss of IgG predominantly occurred in fraction III with an average of 25% (9 batches). Most of the measured antibody activities were similar to that of IgG. The anti‐D antibody showed a lower yield, the mean value of 13 batches was 41 % (SD 11 %), which could be attributed to a higher loss in fractions I and III. The steps in the ethanol fractionation in which considerable losses occurred, were analysed in order to improve the yield of immunoglobulins, especially of anti‐D. Suggestions for modifications leading to improvement of the yield are given.

Abstract. A C1 esterase inhibitor concentrate was prepared in large quantities from fresh human plasma. After removal of the cryoprecipitate and prothrombin complex, the inhibitor was adsorbed batchwise onto an anion‐exchanger. 2.5 g (dry weight) of DEAE‐Sephadex A‐50 was used per liter of ‘plasma’. After extensive washing with 0.15 M NaCl, the inhibitor was eluted from the anion‐exchanger with 2 m NaCl. The eluate was fractionated with ammonium sulphate. The fraction precipitating between 50 and 65% saturation with ammonium sulphate was collected, desalted, sterilized by filtration, and freeze‐dried. The yield of C1 esterase inhibitor was 35%. The method gave a 100‐ to 150‐fold purification on a protein basis. The final preparation contained 2 mg/ml albumin, 6 mg/ml ceruloplasmin and traces of other plasma proteins. The final product passed the test for general safety and was not pyrogenic. To test the effect of the concentrate, 20 ml portions equal in activity to 2 1 of fresh plasma were infused into 5 adults with hereditary angioedema during remission. The activity of C1 esterase inhibitor in the serum of a patient increased from zero to about 75% of normal serum and decreased to about 25% after 24 h. Preliminary observations concerning the risk of transmitting serum hepatitis by the C1 esterase inhibitor concentrate are described.

Abstract. Analysis of the production of plasma protein fraction (PPF) showed a considerable loss of albumin (18 to 25% of the amount present in whole blood) in the cell concentrate after centrifugation of blood and in fraction IV (11% of the amount present in plasma) during ethanol fractionation with a modified Cohn VI method. The recovery of albumin could be increased by washing 10 volumes of cell concentrate, derived from blood centrifuged in a ‘bottle centrifuge’ with one volume of 6% NaCl solution. After centrifugation, 120 ml supernatant per unit of blood is obtained with a protein content of 3%. This diluted plasma is mixed with normal plasma and fractionated according to the modified Cohn VI method. The effect of the described modifications is that the quantity of PPF obtained from blood centrifuged in a ‘bottle centrifuge’ is at least 30% more, not only by the recovery of the plasma proteins formerly remaining in the red cell suspension, but also by a decreased loss of albumin in fraction IV. The final product meets the minimum requirements for PPF. When the blood is centrifuged in a continuous centrifuge, the loss of albumin could be decreased from 18 to 5% by using 2.6% trisodiumcitrate and 0.72% NaCl as an anticoagulant solution instead of ACD and by a lower flow rate.

Abstract. It was observed that during the preparation of normal anti‐D immunoglobulin concentrates by a modified Cohn VI method a considerable loss of anti‐D activity occurred in fraction III. A method was developed to prepare anti‐D immunoglobulin concentrates from fraction III by ethanol fractionation. Three batches were treated on a production scale. An average of 18% of the amount of anti‐D activity present in the original plasma, was recovered, which increased the total yield of anti‐D activity from 44 to 62%. The specific activity of anti‐D in the concentrate thus prepared was 2–3 times higher than that in the normal anti‐D immunoglobulin concentrate. The anti‐D immunoglobulin concentrate prepared from fraction III was diluted with normal immunoglobulin concentrate to reach an anti‐D concentration of 110–120 μg/ml. Using several analytical procedures no essential differences could be demonstrated between this final product and the normal immunoglobulin concentrate. After 8 months of storage at 4°C no significant decrease in anti‐D activity could be demonstrated.