This book responds to dramatic current developments in molecular and cellular biology, and in the increasingly interrelated disciplines of genetics, immunology/immunotherapy and microbiology. Advances in molecular biology, genetic engineering, cloning and DNA sequencing have made it possible to model, design, and produce specific-purpose antibody molecules. This ability to alter molecular/protein structures, and even create new "tailor-made" molecules and proteins, is a quantum leap for both basic science and clinical medicine. This study shows the applications of engineered antibodies in diagnosis immunotherapy and protein purification, and provides insights into the structural basis of antigen binding, effector functions, and regulation of the immune response. These therapeutic and practical uses of antibody engineering are possible by focusing on established as well as emergent concepts, methods and techniques.