Effects of red cell storage and lysis on in vitro cytokine release.

Cytokine release in whole blood assays is inhibited by addition of supernatants from stored blood components in a storage time dependent manner. This is also observed after prestorage leucofiltration of the blood. The role of erythrocyte changes during storage is unknown. In this study, we have therefore used prestorage leucofiltered buffy coat-depleted red blood cells stored for 35 days. Assays of whole blood with addition of either complete suspension or only supernatant from the stored blood units were stimulated with lipopolysaccharide (LPS) and incubated. Additionally, samples from the stored blood units were partly haemolysed and added to similar whole blood assays. After incubation, tumour necrosis factor-alpha (TNF-alpha) and interleukin-10 (IL-10) concentrations were determined. Results showed that the TNF-alpha release was not changed by addition of supernatants from prestorage leucofiltered blood, but significantly decreased with addition of red cell suspension in a storage time dependent manner. The IL-10 release increased with storage time with addition of both red cell suspension and supernatant. The TNF-alpha/IL-10 ratio decreased with storage time, but significantly more, 25% vs. 10%, during the 35 days, with addition of suspension compared with addition of supernatant. TNF-alpha and IL-10 release was not changed by addition of supernatant from lysed erythrocytes of various storage times. Therefore, storage time dependent inhibition of immune response by red cell suspension may in part be dependent on red cell presentation, and may cause some of the side effects by transfusion of red cells.