Do you ever wonder if the reagents that you get from a vendor or a colleague down the hall are good enough for your immunoassays? Do you wonder if immunoassay kits you buy from vendors are the same from lot to lot? You should ask critical questions of vendors and internal sources of reagents. Reagents are the heart of your assays and their characteristics should be checked until you are satisfied that you have a stable, reproducible supply. After all, how do you know if that assay you purchased from a vendor is going to perform the same as the last time until you analyze your precious sample using that reagent as part of an assay?
The Ligand Binding Assay Group of the American Association of Pharmaceutical Scientists has published a paper with recommendations on how to characterize and monitor your critical reagent supplies. In this paper you’ll learn about recommendations for critical reagents for antibodies, engineered proteins and conjugates of antibodies/proteins/peptides.
Here are some recommendations you should think about when you source immunoassays or antibodies from suppliers:
- Just remember, antibodies are produced by biological systems so don’t expect different lots to be exactly the same.
- You should perform your own qualification beyond what’s listed on the data sheet the vendor supplies.
- If the information is not on the vendor’s qualification sheet, ask their representative or technical support group for additional information that is critical to you. If they can’t or won’t provide it, you may want to look for another vendor.
- If you’re buying monoclonal antibodies (MAbs) or kits containing MAbs, run SDS-PAGE and native PAGE to confirm the reagent purity and the appropriate molecular weight of the antibodies. You should also perform an isotyping assay to ensure the MAb is truly monoclonal and is of the appropriate IgG subtype.
- If you’re binding the MAb to a substrate you’ll want to know the true concentration of the MAb to ensure consistency of your conjugation/coating. You can trust the vendor or spend a little bit of extra time to run a protein concentration assay on the reagent your for peace of mind.
- Once you’ve established that the supplier can consistently deliver the quality of the assay or antibodies that you need, then you can reduce your testing as you receive new batches.
These are just a few of the things you need to think about when building or using assays that are critical to your work.
How do you assess the performance characteristics of assay kits or reagents such as MAbs?