A monoclonal antibody demonstrating specificity for drug-resistance cells.

We have described a monoclonal antibody with specificity for permeability-altered drug-resistant cells. This gamma G2b antibody was characterized by antibody-mediated complement-dependent cytotoxicity and by immunofluorescence analysis using a flow cytometer-cell sorter. Further experiments with the flow cytometer showed that vinblastine=resistant cells exposed to that drug had a wider range of fluorescence intensity and had a modal channel 4 times as bright as the same cells cultured in growth medium. We believe that this monoclonal antibody recognizes part of the "P' glycoprotein found on drug-resistant Chinese hamster ovary cells.