Sanne Hoeks

Cytokine assays 95 6 CONCLUSIONS By understanding how factors can manipulate cytokine levels and plugging in the necessary controls or methodology, an objective view of cytokine levels within a disease process can be reached, enabling clear results and definitions that will all culminate in achieving optimal biomarker function of these molecules. We recommend that, especially in the context of clinical trials, sample handing and processing should be done in a standardized way with all individuals undergoing identical practical and handling procedures. In general, different blood sampling tubes can be used however, the tube type within a study should remain the same. Furthermore, directly after sample collection, we recommend keeping samples on ice or at 4 °C before sample separation. The process of sample separation should then be performed as quickly as possible and the products of this separation should be stored at -80 °C for long term storage. When performing cytokine analyses, depending on the sample origin, the matrix interference can be dealt with by removing impeding substances, such as auto antibodies, or by choosing reagents which result in the lowest interference during the assay. By following this general outline, data produced within a study will provide a clearer representation of cytokine levels in patients and allow maximum data mining to be achieved. Acknowledgments This work was supported by Understanding Childhood Arthritis Network (UCAN), Center for Translational Molecular Medicine (TRACER), Top Institute Pharma (T1-214) and Technology Foundation STW (Stichting voor de Technische Wetenschappen). None of the funding sources had a role in either in study design, collection, analysis and interpretation of data, nor in the writing of the report and in the decision to submit the article for publication.