This volume of Advances in Clinical Chemistry highlights current research and applications in the cytokines, chemiluminescence, estrogen and progesterone' receptors, Human Leukocyte Antigen (HLA) and transplantation, and glutathione S-transferases (GST). In view of the expansion of the field of cytokine biology with the cloning and sequencing of many new molecules, the article on cytokines discusses some general principles and reviews areas of potential import to clinical chemistry, 'including the management of disease, specifically in graft rejection, inflammation, and sepsis. The chapter on chemiluminescence introduces the phenomenon and presents analytical applications and recent innovations in high sensitivity clinical assays and nucleic acid detection methods. The role of estrogen and progesterone receptors and receptor proteins in the study and treatment of breast cancer is examined in the third contribution to this volwne. The fourth chapter brings up to date research in the HLA system and transplantation, specifically with respect to the immune response, renal transplantation, and bone marrow transplantation. Chapter four also surveys historical perspectives and presents directions for future developments in HLA and transplantation research. Finally, chapter five provides a broad understanding of the biochemical and molecular properties of GST, examines the value of GST measurements, and points to fruitful areas of future research