[Exploration of cytokines in inflammation in biological fluids]

Accurate and sensitive methods for the measurement of acute phase cytokines (IL-1, IL-6, IL-8, TNF alpha, LIF) in biological fluids are an absolute prerequisite for a proper use of these mediators in clinical practice. Nowadays, numerous kits are commercially available for cytokines quantitation, but one must be very aware of the difficulties in the study of these molecules. The authors describe the various 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, the study of the ability of cells to produce cytokines and the in situ detection of cytokines using molecular biology constitute helpful complementary techniques to the measurement of circulating cytokines.