Whole-blood culture is a valid low-cost method to measure monocytic cytokines - A comparison of cytokine production in cultures of human whole-blood, mononuclear cells and monocytes

Whole-blood and peripheral blood mononuclear cell (PBMC) cultures are used as non-validated surrogate measures of monocytic cytokine production. The aim of this investigation was to compare ex vivo cytokine production from human whole-blood and PBMC with that from isolated monocytes. We also assessed the intra- and inter-individual variation in cytokine production. In 64 healthy men (age 19-40 years) IL-6, TNF and IL-10 were measured by enzyme-linked immunosorbent assay in supernatants from whole-blood, PBMC and monocytes cultured 24 h with lipopolysaccharide (LPS) or UV-killed L. acidophilus. Cytokines produced from whole-blood was found to be more strongly correlated with monocytic cytokines than cytokines from PBMC, particularly after LPS-stimulation: r = 0.57, P < 0.001 versus r = 0.33, P = 0.01 for IL-6 and r = 0.43, P < 0.001 versus r = 0.30, P = 0.02 for TNF-α. Adjustment for a preceding 8-week dietary fatty acid-intervention did not change any of the associations. Based on measurements at three time-points 8 weeks apart the intra-individual variation was ≥ 50% smaller than the inter-individual variation (P < 0.05) in most whole-blood cytokine responses and LPS-stimulated IL-6 from PBMC. We conclude that whole-blood cultures are well-suited low-cost proxy-measures of monocytic cytokine production. Moreover, large inter-individual variation in cytokine production was demonstrated whereas the individual responses in whole-blood were reproducible even over long time-periods.