Cytokine production in whole blood ex vivo

Interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha) have been reported to contribute to the pathogenesis of many inflammatory diseases, e.g., rheumatoid arthritis. As monocytes are believed to be the primary source of these cytokines in peripheral blood, the present study was conducted to establish ranges and patterns of IL-1 beta and TNF-alpha secretion. Using heparinized unseparated whole blood obtained from normal human volunteers, peripheral blood monocytes were stimulated with Sal. minnesota LPS or BSA/anti-BSA immune complex-coated beads (BSA-beads). ELISAs for IL-1 beta and TNF-alpha were employed to quantitate cytokine levels in blood plasma without performing arduous and time-consuming extraction procedures. Over the course of a 6 hr incubation, LPS elicited a dose-dependent increase in TNF-alpha and IL-1 beta production. Preincubation of whole blood with interferon-gamma prior to the addition of a suboptimal dose of LPS or BSA-beads resulted in a synergistic potentiation of IL-1 beta/TNF-alpha production. Dexamethasone, utilized in the treatment of rheumatoid arthritis, proved to be a potent inhibitor of cytokine biosynthesis in whole blood ex vivo. The measurement of cytokine biosynthesis in a relevant physiologic environment not only avoids non-specific monocyte activation, but also may increase our ability to predict clinical outcomes in rheumatoid arthritis and/or other inflammatory diseases.