A guide to the use of immunoglobulin reagents in the laboratory. It provides background, context and step-by-step instructions for techniques that range from choosing the right antibody and handling it correctly, to the proper methods for characterizing antigens in cells and solutions. Also included are chapters on tagging proteins and epitope mapping. Rather than presenting an array of solutions for working with antibodies and antigens, the book instead identifies in each case the best approach to specific problems. These recommendations include more detail in the protocols, extensive advice on avoiding and solving problems, information regarding proper controls, and detailed illustration of theory, methods and results - both good and bad. The manual also includes a set of Portable Protocols - step-by-step instructions for the most frequently used and essential techniques printed on spill-proof cards that can be annotated and used directly at the bench.