In his revolutionary book The Structure of Scientific Revolutions, Thomas Kuhn describes the nature of scientific progress, and how new, better answers to scientific problems become validated and accepted. Progress, he suggests, comes from the construction, and frequent revision, of models or paradigms that explain sets of information. These paradigms are the underlying assumptions of any scientific field. It is significant that Dr. Kuhn's philosophical constructions continue to attract attention and have helped organize thinking in a number of complex fields, including immunology.

It has become clear to me in the preparation of this monograph that a new immunological paradigm is emerging that relates to the participation of the products of arachidonic acid metabolism in the immune response. It is now clear that the prostaglandins (particularly PGE2), the leukotrienes (particularly LTB4), and probably the lipoxins act as primary and/or secondary mediators in a wide range of immune functions and disease states. Synthesis of this paradigm began with the observations of many individuals, then progressed to reviews on mediator involvement in specific diseases or cell types, and finally to recognition of the ubiquity of the prostaglandins and leukotrienes in normal and abnormal immune responses.

Our understanding of the exact nature and importance of the participation of these mediators in immune function is in its infancy, however, and some important basic questions have not yet been answered to everyone's satisfaction. Before any system can be manipulated to clinical advantage, it must be understood.