Thermal stability of cytokines: A review

Background: The role of cytokines in various disease states is a burgeoning field of academic study and clinical application, however there are no consensus documents on how certain cytokines should be stored prior to quantification. This information is especially of interest to researchers assembling a biobank or clinicians who have to transport specimens to a different location in order to be tested. Objective: To review the literature and synthesize prior findings on cytokine storage and freeze/thaw stability. Design: We searched PubMed for articles related to cytokine storage stability. All articles were analyzed for cytokines studied, source of reported cytokine concentration (i.e., human whole blood or serum, concentrations from other species or bodily sources were excluded), and reported statistical results. Results: We identified and synthesized results of 23 peer-reviewed articles which published data on the storage and freeze/thaw stability of 33 different cytokines and chemokines. Conclusion: There is a wide variety of reported cytokine storage and freeze/thaw stability. Interleukin-6 and tumor necrosis factor alpha are the most widely studied cytokines in regard to temperature stability. In a few cytokines, a clear consensus can be reached as to storage safety at particular temperatures, but in most, more research needs to be done and we advise the clinician or researcher to use caution in interpreting cytokine concentration results after a long period of storage or several freeze/thaw cycles.