Accumulation of sCD40L in stored A-Plts and LR-PRBCs and NLR-PRBCs. (A) A-Plts were serially stored according to AABB standards, plasma samples were obtained and separated from the cells by centrifugation, sCD40L concentration (ng/mL) was measured by commercial ELISA, and fresh, heparinized plasma taken from healthy donors was used as a control for sCD40L concentration. The sCD40L concentration in A-Plts was significantly greater at days 1, 3, 5, and 7 of storage in the A-Plts than in FP (P < .05; n = 5). Moreover, the levels continued to significantly increase on days 3, 5, and 7 compared with day 1. However, the concentrations of sCD40L on day 5 compared with day 7 were not significantly different from one another (P < .05). *Statistical significance from FP (P < .05); ¥,§Significance from day 1 (#) (P < .05). (B) Accumulation of sCD40L in PRBCs in which 50% of the unit (by weight) was leukoreduced (LR) and 50% was unmodified (NLR) before storage. sCD40L concentrations (ng/mL) were measured serially in LR-PRBCs and NLR-PRBCs on days 1, 28, and 42. Day 28 and day 42 NLR (hatched bars) were statistically significant (P < .05; n = 5) compared with day 1 NLR. Days 28 and 42 NLR were also significant from days 1, 28, and 42 LR (solid bars). *Statistical significance (P < .05) compared with day 1 of storage.