Selecting Antibodies to Cell-Surface Antigens Using Magnetic Sorting Techniques

As described in other chapters, the selection of phage-displayed immunoglobulin (Ig) fragments with desired specificity can be accomplished through successive rounds of panning on purified antigen (Ag). However, for many applications, the target Ag may not be able to be purified because its identity is unknown (e.g., a putative stem cell or tumor-specific marker) or because the process of purification destroys its native conformation (e.g., in the case of some integral membrane proteins). In such experimental systems, methods that select phage-displayed Ig directly on intact cell surfaces are required.