Phage Display and Subtractive Selection on Cells

Phage display is a powerful tool to select antibodies for conformation-specific epitopes from antibody libraries. Based on the M13 pIII phage display technology we describe a cell suspension-based strategy, which allows panning against complex, multimeric, fully functional cell membrane epitopes without alteration of structure due to purification or immobilization. The method requires a subtractive panning strategy to avoid selection of phage that bind to the plethora of cell surface epitopes that are are not targeted. The panning can be carried out in fully physiological ex vivo conditions, so that the functional properties of the cells and the surface receptors can be preserved and thus phage can be specifically depleted or selected for neo-epitopes exposed after physiological alterations of the targeted molecules. This subtractive panning strategy is described in detail in this chapter and allows for the specific selection of single-chain antibodies directed against functionally regulated epitopes on cell surface molecules.