CYTOKINE GENERATION IN STORED, WHITE CELL-REDUCED, AND BACTERIALLY CONTAMINATED UNITS OF RED-CELLS

Background: Proinflammatory cytokines were measured in the supernatant portion of stored, bacterially contaminated, and/or white cell (WBC)- reduced units of red cells (RBCs). Previous studies from this laborato ry and others have shown that cytokines are generated in platelet conc entrates during storage. This earlier work has been expanded to the st udy of stored RBCs. Study Design and Methods: Units of AS-1 RBCs (n = 10 non-WBC-reduced; n = 10 WBC-reduced) were obtained from a regional blood center, and each was split on Day 3 of storage into three equal portions by sterile techniques. One portion was kept sterile (control) , and the other two were Inoculated with Yersinia enterocolitica and S taphylococcus aureus, respectively, at 1 to 3 colony-forming units per mt. The RBCs were stored at 1 to 6 degrees C for 42 days. Sequential samples were taken during storage and assayed for interleukin 8 (IL-8) , interleukin 1 beta (IL-1 beta), interleukin 6, WBC count, and bacter ia count. For the WBC-reduced group (n = 10), WBC removal was done by filtration on Day 3 of storage, before bacterial inoculation. Results: IL-8 was detected in the supernatant portion of all 42-day-old, non-W BC-reduced (mean WBCs = 4760 +/- 3870/mu L) units of AS-1 RBCs at leve ls ranging from 63 to 1610 pg per mt. By contrast, at 2 to 3 days of s torage, lower levels of IL-8 (range, 0-280 pg/mL) were detected in the same units. IL-8 levels increased progressively during storage in mos t (7/10) units. The highest mean levels of IL-8 were reached by outdat e at Day 42. Y. enterocolitica-contaminated units had statistically hi gher levels of IL-8, with a range of 170 to 2100 pg per mt, by 42 days of storage. S. aureus grew poorly in stored units of RBCs and failed to further stimulate cytokine production. No WBC-reduced unit (mean WB Cs = 0.5 +/- 0.6/mu L), even when contaminated with bacteria, had more than 260 pg per mt of IL-8. Although IL-1 beta was not detected in an y unit of RBCs at 3 days of storage, it increased to low levels (5-13 pg/mL) in all units tested at 42 days, Interleukin 6 was not detected in any unit at any storage time. Conclusion: IL-8 and IL-1 beta accumu lated in the supernatants of stored RBCs despite cold storage conditio ns. IL-8 reached levels >1000 pg per mt in the supernatants of some RB C units. IL-beta increased to significant but low levels (<13 pg/mL). WBC filtration early in storage prevented the accumulation of IL-8. Th e physiologic significance to transfusion recipients of IL-8 in RBC su pernatants is currently unknown and deserves further investigation.