[Methods for studying cytokines in biological media]

Accurate and sensitive methods for the measurement of cytokines in biological fluids are an absolute prerequisite for a proper use of these mediators in clinical practice. The authors describe the numerous molecular forms under which cytokines can possibly circulate. The potential influence of inhibitors (autoantibodies, soluble receptors) on cytokine assays is discussed. Blood collection for cytokines needs a particular attention to prevent a possible contamination by endotoxins which can trigger cytokines cellular production after sampling. If bioassays historically preceded immunoassays, these last techniques are now very popular, but there is an urgent need for standardisation between the different kits commercially available. In addition, in situ detection of cytokines using molecular biology is an helpful complementary technique to the measurement of circulating cytokines.