Effect of blood storage conditions on leucocyte intracellular cytokine production.

Intracytoplasmic detection of leucocyte cytokines has become a powerful tool for the characterisation of cytokine-producing cells in heterogeneous cell populations, however the effect of specimen storage conditions is unknown. The aim of this study was to determine the effect of whole blood stored at room temperature (RT) or 4 degrees C, on intracellular cytokine production by T cells and monocytes. In cell cultures stored at RT or 4 degrees C for 24h, significant changes in several leucocyte cytokines/chemokines were shown compared to blood cultures stimulated at time=0. There was a significant decrease in IL-2, IL-4 and TNFalpha production by CD4+ T cells in blood cultures stored at RT but an increase in IL-2 in cultures at 4 degrees C. There was a significant decrease in TGFbeta production by CD4+ and CD8+ T cells in cultures kept at RT or 4 degrees C. There was a significant increase in MCP-1 and MCP-3 production by monocytes in blood cultures kept at RT or 4 degrees C. There was a decrease in IL-12 production by monocytes in cultures kept at 4 degrees C, whereas IL-10 production was decreased at RT and increased in cultures kept at 4 degrees C. Blood stored at 4 degrees C showed less immunomodulatory changes than blood kept at RT although overall a possible Th1 bias at 4 degrees C.