Summary A method is described for the preservation of red cells in the frozen state. By freezing in liquid nitrogen, it is possible to obtain after freezing and thawing, high recoveries of red cells with a low concentration of glycerol as a protective additive. Without special equipment the removal of glycerol from the thawed red cells can be carried out by washing with 16% sorbitol in a 0.9% NaCl solution. The viability of the processed red cells as shown by their metabolic properties, osmotic fragility and posttransfusion survival is very satisfactory. Résumé Une méthode pour la conservation des globules rouges est décrite. Par congélation en azote liquide il est possible d'obtenir un rendement très haut de globules rouges après congélation‐décongélation par Taction protective d'une concentration basse de glycérol. Sans utiliser un appareil spécial il est possible d'éüminer le glycérol des globules rouges décongelés, en se servant de sorbitol à 16% dans une solution NaCl à 0,9%. La viabilité des globules rouges est excellente, ainsi que l'indiquent les propriétés métaboliques, la fragilité osmotique et la survie après transfusion. Zusammenfassung Es wird eine Méthode zur Konservierung von Erythrozyten auf lange Dauer beschrieben. Gefrierung mit flüssigem Stickstoff gibt die Müglichkeit, nach Gefrierung und Auftauen, eine hohe Ausbeute von Erythrozyten zu bekommen, indem eine niedrige Konzentration von Glycerol als schützende Substanz verwendet wird. Ohne spezielle Apparatur kann die Entfernung von Glycerol mit 16% Sorbitol in einer physiologischen Kochsalzlüsung vorgenommen werden. Die Lebensfähigkeit der Erythrozyten wie indiziert durch die metabolischen Eigenschaften, die osmotische Fragilität und das Überleben nach Transfusion ist ausgezeichnet.

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Abstract. In this article a technique is described for the cryopreservation of human lymphocytes employing a programmed cooling device. A preset temperature curve was used which compensated for the heat exchange during crystallization. The influence of this method of lymphocyte preservation on a variety of the in vitro functions of these cells was evaluated by means such as the lymphocyte transformation test, CML and investigations for lymphocyte membrane markers. All the lymphocyte functions that were tested were found to be retained in full.

Abstract. A method is described for the preparation of leucocyte poor red cell suspensions for transfusion. In this method a plastic bag system is used, consisting of 4 plastic bags filled with all the solutions necessary for the dextran agglomeration technique. The donor packed cells are allowed to flow into this system and the inlet tube is sealed. Consequently all manipulations are performed in a ‘closed’ system, which prevent bacterial contamination. The very short time (15 min) necessary for the sedimentation steps is the fundamental difference with earlier described methods of dextran sedimentation. The described procedure makes it possible to obtain ‘leucocyte poor’ blood with relative ease and without specially instructed technicians. Approximately 1% of the leucocytes remain in the treated packed cells, the red cell recovery is over 80%.