With growing utility for serum cytokine measurements both clinically and in research, there are questions asked about the relationship between storage conditions and freeze-thaw cycles and accuracy of results.
The effect of freeze-thaw cycles on cytokines in serum is varying. Repeated freezing and thawing by up to two cycles will not affect serum cytokines. In case of serum interleukin-10 and interleukin-18, up to 5 freeze-thaw cycles will not affect the concentration of these two cytokines. For more information on this subject you may want to refer to the article attached below.
In general, serum samples for cytokine estimation may be aliquoted and stored at -80°C until analysis. Before analysis you may thaw the serum samples. This will minimize freeze-thaw cycles and in turn prevent degradation of cytokines.