We have plasma samples kept in liquid nitrogen for seven years. Can they still be used to measure cytokines? We are very interested in measuring IL-1, IL-18, and any other related cytokine (IL-6, TNF-alpha). Additionally we would like to measure any endothelial activation marker (any of endocan, sICAM-1, sVCAM-1, sE-selectin and sP-selectin).
I would thank any resource that you can suggest to me.
Hi Enrique I have used plasma samples that were stored at -80 for 10 years for further checks. I re-screened some cytokines done previously to see if samples were fine. There was no change in the IL-6, IL-10 and IFNg levels. Bet the samples stored in liquid nitrogen will be fine for cytokine screening. I did not monitor the ICAMs and selectins.
I agree with Edmund. You can use the samples stored for many years for cytokine analysis. However if the samples have been used before or defrosted they will not work!
I studied protein degradation (delicate polymer readily inactivated) over a course of two years at various temps, 4, -20 and -80 degrees. Minus twenty was unsatisfactory after a couple of months, but minus 80 seemed immortal. All parameters of the minus 80 matched a few liquid nitrogen samples at termination-- it's most likely your samples are as good as the day they went in, barring any contamination from vessel or media.
I recommend that the control also be treated with the liquid nitrogen storage prep.
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