Idiotypy in Biology and Medicine aims to serve the increasing interest and involvement in the practical aspects of idiotypy in biological systems. The concept of idiotypy has received wide recognition and interest far beyond the area of immunology. Experiments and interpretation of findings, reported here, clearly support the general nature of the idiotype concept in manipulating biological systems to correct pathological conditions or to improve the immune adaptation to environmental factors. The book is organized into three sections. Section 1 discusses original concepts of idiotypic manipulations. It reviews old and recent data important for the concept of an idiotype network and reports on attempts to deal with the T-cell receptor paradox; explains the immune system in terms of a circular idiotype network that can be demonstrated by sequential immunization; and emphasizes the need for restrictions in network interactions. Section 2 addresses the role and activity of idiotypic and antiidiotypic antibodies in the regulation of the immune system. Section 3 takes the issue of idiotype-antiidiotype out of the realm of the immune system and discusses it as a new principle to analyze and manipulate biological systems in general.