What is the specific activity and how is it determined?
Specific activity (expressed in units/mg) is a function of cytokine or growth factor purity and appropriate protein folding. To determine the specific activity, typically the readout of cytokine treatment is measured in a standardized bioassay. The ED50 (expressed in ng/ml), which is the concentration of cytokine or growth factor required to induce half the maximal biological response is determined in the assay.
