of. and biological activity ascribed to, the different leukolysins. Therefore, we sought to present a comprehensive review of the leukolysins currently under intensive study and to compare and contrast their biological activities in an attempt to clarify the nature of these diverse biological species. This book is intended for both immunologists conducting basic research and clinical oncologists, since it reviews not only the clinical applications of the leukolysins, but presents a current update on those leukolysins that are in early developmental stages of research and could enter into clinical trials in a few years. The introduction gives an overview of the status of research on the leukolysins. In the first section, the biological activities and biochemical characteristics of the leukolysins are presented. The lymphokines.