Figure 3.

Examples of reported antibodies and screening methods with pharmacological relevance. (A) Bispecific antibody against HER2 and CD3 linked together through an UAA. The basic principle of a bispecific antibody is that it can bring two targets together. Our immune system can eradicate cancer cells, through recognition by killer immune cells that destroy them (Chames and Baty, 2009). As depicted, a bispecific antibody can bring cytotoxic T cells in contact with the cell surface receptor HER2, frequently found over-expressed in breast cancer cells (Kim et al., 2012). (B) Structural overview of an antibody drug conjugate (ADC). Through specific targeting of a plasma membrane marker (example: fibronectin, a marker of tumor angiogenesis) a bound drug (example: cytotoxic drug) can be released to the targeted marker (Bernardes et al., 2012). Until now, only natural amino acids, like cysteine, are used to conjugate cytotoxic drugs to the antibodies through thiol-bonds. (C) Antibody library formats in E. coli are used to screen for antibodies with improved affinity for their antigen. The antibodies are expressed in E. coli and displayed on the inner-membrane. By outer-membrane permeabilization the antibodies are exposed and suitable for FACS-mediated sorting with fluorescently labeled antigens (Mazor et al., 2010).