View the protocol to prepare test samples using Fab-ZAP secondary conjugates here.
While we have not done a titration of the Fab-ZAP line of products, we have tested their cytotoxicity at the maximum concentration used in our in-house assays (45 ng/100 µl, 96-well plate), and have not see any non-specific killing.
However, with Daudi cells in flow cytometry, we do have some data indicating that the Fab-ZAP (human) binds the cells non-specifically. This appears to be a result peculiar to Daudi cells for undetermined reasons. Fab-ZAP (human) on non-human cell lines has not resulted in non-specific cytotoxicity.
In general, this line of products is used as a diagnostic tool with antibodies that are of a particular host species targeted to an alternate species, so the non-specific binding possibility is negligible. Additionally, there are cell lines that are particularly sensitive to Saporin, and Daudi cells may fall into that category, such that it would be a very good idea to titrate the Fab-ZAP product for your own individual application and use.