GENERATION OF A MONOCLONAL-ANTIBODY TO P-GLYCOPROTEIN PEPTIDES USING TUBERCULIN-PPD AS A CARRIER

A novel immunization protocol together with stringent selection criter ia have been employed to generate a new murine monoclonal antibody ('' D8'', isotype IgG(1), kappa) which specifically recognizes the human p 170 drug resistance glycoprotein. This antibody is directed towards a defined peptide sequence located in the -COOH terminal region of the f irst external loop of the molecule. It is reactive with its epitope wi thin the intact native glycoprotein in formalin-fixed and conventional ly processed histological tissues, in flow-cytometric preparations and by Western blotting. The antibody precipitates tares its target pepti de sequence from solution, and thus may be a useful reagent with which to establish an ELISA, RIMA or other similar assay. The peptide epito pe recognized by this monoclonal antibody is restricted to the human M DR1 gene product and is not contained within the rodent homologue of t he P-170 molecule. Immunohistochemistry has consistently failed to det ect this epitope in rodent tissues? thus confirming that it does not e xhibit the cross-reactivity of other currently available anti-P-glycop rotein monoclonal antibodies. The experience of this study emphasizes the value of the tuberculin-PPD (purified protein derivative) immuniza tion protocol as a powerful strategy when generating monoclonal antibo dies to small synthetic peptides. The resulting monoclonal antibody (D 8) will be an invaluable reagent with which to analyse P-170 glycoprot ein expression when assessing the role of multidrug resistance in huma n cancers.