Hello all,
I have supernatants containing IFN-alpha protein at concentrations in pg/ml...I want to use them in PBMC stimulation assays...kindly tell me conversion procedure of pg/ml to IU for IFN-alpha.
Hi Ashwini,
the IU is derived from an activity-based assay that yields different results from batch, lot and company. Thus, there is no formula to directly derive IU from pg/mL. However, most company used standardized assays like A549/ECMV for human IFN (see the linked publication).
Generally, you will have the information about the number of units in a vial or the minimum activity in the product sheet. From there, you can workout the relationship between units and concentration.
So, in your situation, a way to determine your IU would be to do a standard curve using recombinant IFNa that has a known IU/mL and to compute the IU of your supernatants. This would not account for the individual potency the IFN in your sample but would enable you to make your comparison.
You could also run a protection asssay (A549/ECMV) to titer the units present, but it will be work intensive and would probably not add anything to your results. So. as long as your results are clear, I don't see, in my opinion, the need to convert an ELISA result to another unit.
Best,
Nicolas
http://www.sciencedirect.com/science/article/pii/S0022175901004604
Thank you so much Mr. Nicolas..I will work out on standard curve as suggested..
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