I am reviewing several MHC-peptide binding affinity predictors trained on IEDB data. Quantitative records for MHC class I allotypes come from a lot of different assays and, by extension, have different measurement types. Here are the most common measurement type descriptions (I haven't altered them in any way):
- dissociation constant KD (~IC50)
- dissociation constant KD (~EC50)
- half maximal inhibitory concentration (IC50)
- dissociation constant KD
- half maximal effective concentration (EC50)
All of the predictors I've reviewed so far consider these measurement types interchangeable, which I find extremely odd. While IC50 and EC50 can indeed be similar under certain experimental circumstances, I find it hard to believe that any one of these can be approximately equal to Kd (this site already has a post on this matter). I've contacted several authors and database curators, and all of them have assured me that these values can indeed be considered more-or-less interchangeable, but I can't find any references to support these claims.