Q: Using Mab-ZAP (Cat. #IT-04) in a cytotoxicity assay, I obtained a nice dose-response curve up to around 10-9 M of antibody and then lost progressively the toxic effect of Mab-ZAP. What should I do to improve in my assay?
A: If the highest dose for which you got a good response was 10 nM and you lost effect when the primary concentration was increased beyond that, then that is the result we would expect. Often we have seen in cytotoxicity assays that when the primary antibody concentration is raised beyond a certain level (10-100 nM frequently being that level) there is so much free primary antibody that it competes with the Mab-ZAP-bound antibody for binding sites, thereby reducing the toxic effect. We recommend that you pre-incubate your primary with Mab-ZAP before adding the solution to the wells.
Related: Mab-ZAP (Cat. #IT-04)