cytokines in serum

iddavis at iddavis at
Tue Sep 24 08:02:22 EST 1996

In article <reddjo.22.00108F69 at>, reddjo at (Joan Redd) writes:

> 1.  How soon after the blood is drawn must it be processed?  Can it be stored 
> in the refrigerator for any length of time, and if so, how long?

Should be centrifuged and frozen ASAP, preferably within an hour.  Can be
stored pretty much indefinitely at -70.

> 2.  Can the serum be frozen before it is assayed (ELISA) for the cytokines?

Yes, but avoid repeated freeze/thaws so store in small aliquots if possible
to allow reassay.

> 3.  What is the optimum procedure for obtaining the serum?  Are there any 
> precautions that must be taken during clotting, etc.?

I generally use a needle and some sort of enclosed tube...  8^}  No special
precautions aside from sterility of course.  Clotted blood is best.

Be aware that many cytokines are unstable eg TNF-a degrades very rapidly
unless serum is frozen fast.  Also, serum often contains inhibitory factors
so you should do dilutions eg 1:5, 1:10 to see if comparable results are
obtained.  If your calculated value at a 1:10 dilution is greater that that
seen neat or at lower dilutions, you have diluted out an inhibitory factor.
In practice it seems this almost always does happen.

Ian Davis					iddavis at

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