Certain medicines work by inducing different properties of cells. One example is antibody dependent cell-mediated cytoxicity (ADCC). ADCC is a way for the medicine to cause the patient’s own immune system to kill certain harmful cells, such as cancer cells.
ADCC can be measured in assays using immune cells along with cells expressing the protein recognized by the antibody. The immune cells can be cells from human donors or cloned cells grown in a laboratory. Counter-intuitively, laboratory cells can provide a test which is more sensitive to differences between products than using cells from human donors. Human cells include a mixture of cell types, not all of which can participate in ADCC. In addition, normal genetic variation can cause differences from donor to donor.
Furthermore, multiple uses of less sensitive testing methods can provide more data which might give the impression of more information, but can actually provide less insight. For example, the extent of ADCC that a product induces is dependent on the amount of certain types of carbohydrates (glycans) attached to the product. Therefore, the analysis of the glycans can give important information to scientists about the medicine. This analysis is usually done by removing the glycans from the protein, separating them based on their chemical properties, and quantifying the amount of each. If the glycans which impart this function are not fully separated, they could be missed as they are usually present in small amounts (see below). The full separation of species depends on many factors, including the speed of the analysis. If the analysis is done too quickly, the different types of glycans are not fully separated and important information could be missed. So if a less sensitive method with human cells and a glycan method with low resolution are used, data has been generated, but differences are not detected.