This immortalizes recombinant cDNA clones for expressed Igs. Defined sets of primers specific for the different VH and VL chain–region gene families then allow amplification of all transcribed rearranged variable regions within a given immunoglobulin repertoire for library construction, thus reflecting all antibody specificities in a particular individual. This RNA is reverse-transcribed into cDNA, which is used for PCR of the VH and VL chains of the encoded antibodies ( Figure 1a, b). The key to success is preparation of quality RNA from the cell source chosen (e.g., peripheral blood mononuclear cells). A large antibody library and efficient selection are needed to isolate specific mAbs from a cloned immunoglobulin repertoire. The APD process begins with antibody-library preparation, followed by ligation of the variable heavy (VH) and variable light (VL) PCR products into a phage display vector, culminating in analysis of clones of mAbs. These characteristics make APD a powerful tool to better understand immunological processes and human diseases that involve formation of (auto-)antibodies against defined (self-)antigens. This technique allows in vitro selection of mAbs of virtually any specificity, greatly facilitating recombinant production of reagents for use in research and clinical diagnostics, as well as for pharmaceuticals for therapeutic use in humans (e.g., adalimumab, the first fully human APD-derived mAb) ( Lee et al., 2007).īecause of a physical connection established between the antibody fragment on the outside and the genetic information encoding the displayed protein within the phage, APD also allows comprehensive studies of genetics and function of antigen-specific mAbs. Antibody phage display (APD) is based on genetic engineering of bacteriophages (viruses that infect bacteria) and repeated rounds of antigen-guided selection and phage propagation ( Barbas, 2001). The production of human monoclonal mAbs for research and clinical use is closely related to the development of phage display technology, initially described by Smith in 1985 and further developed by other groups (e.g., Winter, McCafferty, Lerner, Barbas).

Phage display antibody repertoire