Background: Cytokines, because of the nature of their immunoinflammatory actions, are potential mediators of the symptom complex of nonhemolytic transfusion reactions. One possible source of cytokines in the transfusion setting is the stored blood component itself.
Study design and methods: To test this possibility, the plasma portion of stored platelet concentrates (PCs) was assayed for the presence of interleukins 1 beta (IL-1 beta), 6 (IL-6), and 8 (IL-8) and tumor necrosis factor alpha (TNF-alpha). Samples were taken from PCs obtained from the inventory of a regional blood center (n = 120; 30 each of 2-, 3-, 4-, and 5-day-old units).
Results: Detectable levels of IL-8 were measured in 59 percent of the PCs sampled, ranging from 30 percent of the 2-day-old units to 83 percent of the 5-day-old units. The median IL-8 concentration ranged from undetectable levels in 2-day-old units up to 1100 pg per mL in 5-day-old units. The mean IL-8 concentration in 5-day-old units, 11,600 pg per mL, was 100 times the mean for 2-day-old units, which was 116 pg per mL (p < 0.0001). The highest levels of IL-8, 50,000 to 200,000 pg per mL, in general were found in units with the longest storage times and highest white cell counts. Sequential sampling of 17 individual PCs over 7 days of storage confirmed that IL-8 increases progressively with increasing storage time. Parallel, but smaller, increases in IL-1 beta were observed in those units with high IL-8 concentrations. TNF-alpha was detected in 3 (10%) of 30 five-day-old PCs, but never exceeded 55 pg per mL in any unit tested. IL-6 at levels of 740 and 508 pg per mL was detected in two 5-day-old units with high white cell counts of 9500 and 14,800 per microL, respectively, but not in 21 additional units tested with white cells < or = 9200 per microL or storage time of < or = 2 days. White cell reduction by third-generation filters on Day 1 of platelet storage prevented the generation of IL-8 and IL-1 beta to Day 5 of storage.
Conclusion: Although IL-8 achieved levels in some units of PCs that appear capable of causing physiologic changes, the potential adverse effect on transfusion recipients of the infusion of cytokines in PCs remains to be investigated.