This is because I would like to measure the absolute concentration of a few selected cytokines for control and treated-sample (cancer cells) using ELISA kit. With the absolute concentration, I found certain cytokines concentration is similar for both control and treated-sample. After relative the absolute concentration of treated sample to control, we can see clearly the fold change of certain cytokines is significantly higher than control.
As far as I know, in most of the research papers expressed the ELISA result in absolution concentration (pg/ml, ug/ml, etc). Anyone came across with research paper expressed ELISA result in relative concentration after measured absolute concentration? If so, please kindly share me the paper so that I can have a reference.
Hope to hear from anyone of you.
Thank you,
Regards,
Seng
Hi Yuan - Seng Wu,
We had a paper published in the Journal of Immunology of 1998" Expression of Complement Receptors1 and 2 on follicular dendritic cells is necessary for the generation of a strong antigen-specific Ig G response" 1998,160: 5273-5279 , via comparing OD value with a standard curve to calculate relative units(RU) for an IgG response . You may try this way if it is what you looked at.
Hope it will help!
Unless standard curve is prepared with more ditributed points, quantification stands a difficult process. You need to obtain standards as refrenece materials.
I dont understand how if you compare mean levels from control and treated and cant really see a difference, how you could see a difference if you express it as fold-increase concentrations?
You are aware of the fact that you increase the error if you switch from absolute concentration to relative concentration?
Natalie is right, it sounds curious that you can´t find a significant change at the absolute level, only after transforming the values into relative change. It sounds like fishing for significance, sorry for speaking so blunt.
Dear Natalie and Michael,
Please kindly accept my apology for mis-leading you both. For example, I have 3 cytokines to be measured for their protein concentration from supernatant of control and treated-cancer cells. After measured their absolute concentration (derived from standard), I found that two cytokines expressed high in both control and treated-cancer cells, but the latter is still slightly higher than control. While the third cytokine, it expressed low in control and treated-cancer cells, but in comparison treated-cancer cells is significantly higher than control. My objective is to identify which cytokine (among the three) expresses the highest in treated-cancer cells when compared to control. This is the reason why I expressed the data in relative concentration rather than showing in absolute concentration. If I express the data in absolute concentration, then my graph may look weird since the absolute concentrations for the two cytokines either control or treated is high.
Any comment?
O.k., now I understand your intention.
Some graphic programs offer the possibility to change the y-scale within a graph, creating a gap between the lowest and the highest values but I can´t offer you an example because fortunately I didn´t face this difficulty until now.
Dear Michael,
Yes, I know we can do that using graphpad prism, but I choose not. Anyhow, thanks for your precious time to answer my question.
Yes, graphpad prism provides options to proceed with calculations. The variations is best viewed if you use Log-Log transformation than linear curve depiction.
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