Thierry (above) is exactly right. I think this is a common mistake. People routinely analyze serum and conclude it is reflective of circulating factors when in reality it contains significant products from the collected cells, particularly platelets. Plasma, provided it is compatible with your kit, is a better reflection of the systemic cytokine milieu.

Dear Saumyadip,

yes you would get significant difference between plasma and serum, since the activation process that leads to serum production from whole blood will release growth factors and cytokines from blood cells in particular the platelets. Kind regards, Thierry 

I would suggest you to use plasma...

We use plasma (extraction with heparin) in mice because it is easier recoletar plasma than serum. However, we never made a comparative analysis between the two samples. I think may have differences, but this will depend on the sample of interest. Good luck.

Dear Saumyadip,

Primarily depends on the design of their study. In my work I have always done with the serum sample. But as their collections were EDTA, the ELISA procedure can also be done with plasma. Just be aware that the kit used in question give you the possibility of using plasma for this procedure.

Good luck!!

It depends on the cytokine being tested, how the assay was developed, and the anticoagulent used.  There used to be a nice table on differences between serum and plasma cytokine measurements available from Rules Based Medicine (RBM) but I cannot find it on their website now.  You have to decide what is most important to you: consistency or accuracy.  If you are looking for relative differences than just stay use what you are comfortable with all the time.  If you really need accurate measurements then you need to consider all the things others have said about what serum and anticoagulents may do to alter actual cytokine levels or assay recoveries. 

Here are a few papers that might point you in the right direction

Comparison of serum, EDTA plasma and P100 plasma for luminex-based biomarker multiplex assays in patients with chronic

obstructive pulmonary disease in the SPIROMICS study (2014) O Neal WK, Anderson W, Basta PV, Carretta EE, Doerschuk CM,

Barr RG, Bleecker ER, Christenson SA, Curtis JL, Han MK, Hansel NN, Kanner RE, Kleerup EC, Martinez FJ, Miller BE, Peters SP,

Rennard SI, Scholand MB, Tal-Singer R, Woodruff PG, Couper DJ, Davis SM J Transl Med. 2014 Jan 8;12(1):9

Analysis of serum and plasma identifies differences in molecular coverage, measurement variability and candidate biomarker

selection (2012) Alsaif M, Guest PC, Schwarz E, Reif A, Kittel-Schneider S, Spain M, Rahmoune H, Bahn S Proteomics Clin Appl. 2012

May 29

Thierry (above) is exactly right. I think this is a common mistake. People routinely analyze serum and conclude it is reflective of circulating factors when in reality it contains significant products from the collected cells, particularly platelets. Plasma, provided it is compatible with your kit, is a better reflection of the systemic cytokine milieu.

From a simple analytical point, serum is plasma with a set of activates proteases (here coagulation factors). Already this makes a lot of analytes in serum instable. Also plates are activated, ...

The most common reason why people are using serum is a long lasting tradition. For plasma you have to make sure what kinds of plasma can be used in the assay. In some cases EDTA as well as heparin can disturb the test. If it's not described in the package insert, just run a short validation. 

Hi all, i would go for plasma too. It is a better material for measuring cytokines. Whether you want to compare what you get between the two fluids is a different story altogether and maybe there is an interest in it.  EDTA may be a substance that deteriorates your final result. Ww tend to use plasma anyway. What do you use in the very end may be a result of what kind of project do you want to get involved in.

Hope i helped too.

Best wishes,

Nikos

Hi All, I basically agree with the comments that have been made. If you go with plasma determination, the handling of the samples, in particular type of needle for venipuncture, temperature of storage of blood, time between blood collection and centrifugation, g force to remove the blood cells by centrifugation, are all aspects important to consider and which should be well standardized and monitored to avoid artefacts (for instance residual blood cells in the plasma prior to freezing). It is important to obtain a cell-free plasma that has not gone through some activation during blood processing. Once cell-free plasma is obtained you should be able to freeze it at -80°C with no major impact on the cytokine levels. Best wishes, Thierry    

Serum has less proteins than plasma. It might be better use plasma for testing purpose. Clinically we use plasma not serum for any chemistry dignosis.

sam

In order to prevent blood clotting during the preparation of plasma anticoagulants commonly are used (like EDTA or heparin).

In most cases, anticoagulants affect the interaction of antibodies with antigens, so most test systems designed to work with serum, but not with plasma.

I recommend plasma, because clot formation, invisible and visible hemolysis and dying leucocytes may not reflect true profile of Cytokines. Moreover glycosylated cytokines may bind to clot proteins and reduce the true level of cytokines in serum..  

It really depends upon the cytokine being evaluated.  Some levels are artificially elevated with platelet degranulation and/or granulocyte degranulation, both of which occur during the clotting process.  As noted earlier, some will be artificially low due to binding to the thrombus or other proteins.  Most ELISA kits dilute the serum or plasma, so the EDTA in the vacutainer tube usually does not affect the ELISA if it has been validated with plasma.  I suggest you examine the manufacturer's literature for your particular ELISA kit and cytokine to determine whether plasma is a suitable sample and that the kit will serve your purpose.

Dear Sarkar:

The answer of Larissa is absolutely correct. At the same time for cytokine antibodies (IgG  and IgM) compare by titrating both plasma and serum of the same individual and observe the difference.  Keep in mind that standard cytokines are mostly recombinant, with research grade or clinical grade. But natural cytokines are glycosylated.

I dont think there will be any difference.

In science we can not assume. We should test and see!

For cytokine measurements, in my hand, plasma is the way to go...

This depend upon the manufacture standard procedure. If the lot of cytokine kits is standardized with serum it should be done in serum. There is no much of different in value in serum or plasma, because it will compare with your control group.Further if it says serum better you can convert the plasma to serum with adding 10% calcium chloride. The clotting factor will be removes and you will get serum.

In most cases, serum is used for cytokine measurement by ELISA. There is different matrix effect serum/plasma v buffer. The manufacture should provide some information for the kit.

Hello, i agree with most of the answers,in my lab we use plasma, but i spin it down before plating to remove the fibrin (found in plasma not in serum) that may interfere with the assay.  I use both ELISA and MSD (ELISA like method but much more sensitive) to measure cytokines, and had never had a problem with using plasma.

Hope that helps 

My experience is with biorad multiplex plat form.

Best answers are already given. Just keep in mind that some proteins are lost along in the coagulation process and therefore absent in serum while still present in plasma. If your assay is compatible to plasma I would defenately prefer to analyse this but please first compare both in a paralell validation.

I agreed on the most answers above. analysis of serum levels gives you an idea of  the relative differences among the groups or recoveries,but measuring plasma levels would reflect a more realistic circulating factors. If this is a case ,I would prefer to using a platelet - depleted plasma while doing ELISA  analysis.

Plasma protein levels better reflects the circulatory levels. I would go with plasma if compatible with the kit or get a kit that is compatible with plasma. Best of luck. 

Thanks a lot for all your answers. I am now working for the parallel validation to analyze my protein in both serum and plasma levels.

Here is a website on collection that may be helpful. http://technical.sanguinebio.com/considerations-for-measuring-cytokine-levels-in-serum-or-plasma/

I was wondering about this too.  Also, in the past, they often cultured the PBMCs and tested the supernatant - does that give any better results?

We do the cytokines were determined by ELISA in sera only and not working in the plasma!

Thanks to these comments regarding the work of plasma, very instructive for me!

Jasenko,  two possibilities 1) the anti-coagulant as noted above it does make a difference whether you use EDTA, Heparin, or ACD; 2) there is a higher protein content in plasma than in serum and depending on the processing possible platelet contamination.

Thanks a lot! Regards from Sarajevo Jasenko

  Plasma is collected from blood drawn into tubes containing anticoagulants EDTA which chelate calcium ions to prevent coagulation. Serum collection tubes contain clot activators, however this method does not allow collection of peripheral blood mononuclear cells (PBMCs) from the same vial, which means that oftentimes, plasma will be the product of choice to maximize the value of blood drawn in a minimal number of tubes from study participants and healthy donors

Plasma is superior to serum for any humoral assay.Keep in mind interferance of EDTA..

It depends!

Do you know from whom it is produced and where the cytokine you want to study is stored? For example, it is stored inside the platelets?

This is so helpful. I needed to make a decision on whether to use serum or plasma for my assays.

Keep in mind it also depend on what you want to measure in the serum.

99% of the investigators use only serum, although I prefer to use plasma, but for comparative purposes, it is important to use serum and it is also worthwhile one compares serum and plasma for their assays, before coming to any conclusion.