Regeneration of 2,3-diphosphoglycerate (DPG) was determined following transfusion of DPG-depleted group O red cells into group A recipients. Blood from five donors was stored in the adenine-containing solutions CPDA-1, AS-1 or AS-3 for 35 d at 4 degrees C. Post-transfusion red cell DPG and ATP were measured in separated group O red cells over a 7 d period. The studies confirmed rapid in vivo DPG regeneration with greater than or equal to 50% of the maximum level being achieved within 7 h. An average of 95% of the recipients' pre-transfusion DPG level was achieved by 72 h and by 7 d mean (+/- SEM) DPG levels relative to recipient's pre-transfusion DPG averaged 84% (+/- 13%), 92% (+/- 17%) and 84% (+/- 21%) for CPDA-1, AS-1 and AS-3 red cells, respectively. Results were comparable to those previously reported for blood stored in ACD for 15-20 d (Valeri & Hirsch, 1969; Beutler & Wood, 1969). The immediate regeneration rate, V, closely approximated first order regeneration kinetics with AS-3 red cells exhibiting double the rate of CPDA-1 red cells (P less than 0.001). AS-1 red cells exhibited an intermediate rate of regeneration which was not significantly different compared to either CPDA-1 or AS-3 (P greater than 0.05). V exhibited a significant (P less than 0.05) positive correlation with ATP levels 5-7 h post-infusion. ATP regeneration of the infused cells was rapid with a mean increase of 1.2 mumol/g Hb above post-storage levels being achieved 1 h following transfusion.

A new red cell preservation solution is described in which the red cells may be stored for 49 d with greater than 75% mean post-transfusion recovery. Blood is drawn into Anticoagulant Citrate Phosphate Dextrose Solution, centrifuged, the plasma removed and the cells resuspended in 100 ml of a solution containing saline, adenine, dextrose and mannitol (Adsol Preservation Solution, Fenwal Laboratories, Deerfield, Illinois). The final product, AS-1 Red Blood Cells, has a haematocrit of approximately 0.60 and flow properties that are similar to those of whole blood. After storage, red cell haemolysis is minimal and erythrocyte adenosine triphosphate is well preserved. This study documents that red cells may be stored in a protein-poor electrolyte medium for periods of 49 d with good post-transfusion survival.

The precision and reproducibility of 111In and 51Cr platelet radiolabel agents for in vivo kinetic studies of stored platelet concentrates (PC) were investigated. The objective was to develop a precise method with concurrent labelling of two platelet populations using different isotopes, which would allow identification of small differences in in vivo platelet quality. Identical labelling procedures were used to investigate the effects of PC storage age, different methods of red cell (RBC) and white cell (WBC) contamination correction, and label elution correction on the results of 111In and 51Cr kinetic studies. 111In and 51Cr platelet survival curves from the same PC, even when uncorrected for elution and RBC contamination, exhibited excellent correlation, irrespective of the age of the concentrate and its viability. However, slightly higher, but statistically significant, post-infusion per cent recoveries with 51Cr labelled platelets were found. Two factors were identified as the cause for this difference. There was a higher affinity of contaminating RBC/WBC in PC for 51Cr than for 111In. With determination of RBC/WBC activity by centrifugation/density separation, RBC/WBC fractions from the injectate were found to contain 12.6 +/- 3.8% v 7.1 +/- 3.6% of total 51Cr and 111In activity, respectively, in 20 studies. In addition, there was a significantly higher 111In activity in plasma immediately post-infusion than with 51Cr, 5.2 +/- 1.3% v 2.8 +/- 1.6%, respectively, suggesting more label elution or carryover. After correction for the activity of RBC/WBC and for elution or carryover, essentially identical 51Cr/111In platelet survival curves were found. In 31 stored PC studies, the absolute average difference between 51Cr and 111In per cent recoveries was only 4 +/- 3% in a group of donors whose platelet recoveries ranged from 10% to 80%. Similarly, the average difference between 51Cr and 111In survival was only 8 +/- 4 h within a range of survivals from 40 to 220 h. In conclusion, after correction for elution and contaminating RBC/WBC binding, these studies show that 51Cr and 111In may be used interchangeably for labelling of stored PC, and that small differences between test and control platelets could be reliably detected using concurrent labelling with simultaneous infusion.

Platelets show a rapid reduction in their responsiveness to aggregating agents during storage for transfusion, but little is known about reversal of this defect in vivo after transfusion. In this study, fresh and stored platelets from the same donor (n = 12) were labelled with 111In or 51Cr, respectively, mixed, and simultaneously infused. Blood samples were taken for up to 5 d post-infusion, and the functional behaviour of the labelled platelets ex vivo was measured by retention on glass bead columns, and by whole blood aggregability to ADP, epinephrine and ristocetin. Aggregation was determined by filtering aggregated samples through a column of cotton wool to remove the aggregates, and quantitated as per cent decrease in radioactive counts. The study showed that, although infused radiolabelled 5 d stored platelets had a significantly lower aggregability towards ADP and epinephrine immediately (1 h) after infusion (32% and 29%, respectively, of fresh platelet values), a complete restoration to fresh platelet levels was found 24-72 h post-infusion, with no further change observed over the ensuing 5 d with either fresh or stored labelled platelets. A slightly (6-9%) lower adhesion to both uncoated and collagen-coated beads was found for the stored platelets throughout the 5 d period of study post-infusion. In conclusion, these studies show that, with ex vivo testing, platelets stored for 5 d quickly recovered adhesion and aggregability capabilities similar to that of fresh platelets, suggesting that the functional lesion developed during storage is quickly and completely reversed after infusion.