n vitro display technologies have put together the generation of large antibody libraries with selection and screening procedures to identify lead candidates. Phage display antibody libraries allow selecting and identifying binders for a variety of antigens. Nonetheless, the procedure is limited by the possibility to quantitatively follow the enrichment during selection cycles and tune up the clones for specific binding proprieties (i.e., affinity). Yeast display allows the expression of thousands of copies of the antibody on each cell, simultaneously carrying the plasmid encoding that antibody, moreover the selection parameters can be accurately controlled by flow cytometry-based analysis and sorting. The combination of phage and yeast display takes advantage of both platforms by starting with a vast number of antibodies in the phage display selections followed by the precise sorting of the clones specifically recognizing the target of interest. In the present chapter, we illustrate protocols to generate and enrich - using fluorescence-activated cell sorting (FACS) - yeast display antibody libraries, using selection outputs obtained from phage antibody display libraries as starting material. The present methods can be easily applicable for the identification of monoclonal antibodies with desired binding properties.
