Glycogen metabolism in stored granulocytes

Optimal function of transfused granulocytes (PMNs) requires adequate glycogen metabolism. Previous studies in our laboratory suggested that stored PMNs had decreased glycogen. We report here the glycogen content and chemotaxis of stored PMNs, and the ability of fresh and stored PMNs to use glycogen as the fuel source for chemotaxis. PMNs were prepared from 8 fresh units of blood drawn into citrate‐phosphate‐dextrose‐ adenine, suspended at 2 or 8 × 10 7 PMN per ml in autologous plasma with or without 15 m M sodium bicarbonate, and stored at 22 to 24°C in transfer packs for 48 hours. Glycogen was measured on resting PMNs, and after challenge with opsonized zymosan and F‐Met‐Leu‐ Phe (FMLP). The chemotaxis of fresh and stored PMNs was measured in the presence or absence of extracellular glucose. Fresh PMNs contained 10.3 ± 0.5 (mean ± SEM) μg of glycogen per 10 6 PMN. Glycogen decreased by 4.2 ± 0.9 μg per 10 6 PMN after challenge with opsonized zymosan and by 1.1 ± 0.6 μg per 10 6 PMN after FMLP. After 48 hours of storage, neutrophil glycogen increased by 18 percent, except in units stored at a concentration of PMN of 8 × 10 7 per ml without sodium bicarbonate. In PMNs from these units stored without bicarbonate, glycogen decreased by 9 percent (p < .05), and there was a 19 and 55 percent decrease in the ability of PMN from these units to metabolize glycogen after exposure to opsonized zymosan and FMLP, respectively (p < 0.05). In addition, in PMNs from units stored at a concentration of PMN of 8 × 10 7 per ml without bicarbonate, there was a 47 and 70 percent decrease in chemotaxis at 24 and 48 hours, respectively (p < 0.05). The chemotaxis of PMNs from all units was decreased, when measured in the absence of glucose (fresh PMNs, 10.3% decrease in chemotaxis without glucose; 24 hours storage 24 ± 2% decrease; 48 hours storage, 32 ± 3% decrease). We conclude that 1) storage of PMNs for 24 hours is accompanied by increased glycogen content, except in units stored at high concentration; 2) glycogenolysis stimulated by phagocytosis or a chemotactic stimulus is attenuated after storage; and 3) chemotaxis of PMNs suspended in glucose‐free medium is also somewhat decreased after storage. From these data, we also conclude that the functional and metabolic changes which accompany storage of PMNs, either at low or high cell concentration, are not due to insufficient glycogen stores and that, while defective glycogenolysis may slightly impair the chemotaxis of stored PMNs, it is not the major cause of impaired chemotaxis in PMNs after storage.