67 – Cytokine Biology

Cytokine biology is infiltrating all aspects of surgical science, as it becomes evident that these mediators are intimately involved in the inflammatory response. With the current sequencing of the human genome, the number of cytokines discovered has increased dramatically. Immunoadhesins and antibodies are two examples of anticytokine-based therapies. The study of cytokine biology has also revealed how some cytokines can counteract the action of other cytokines. This takes advantage of the property that the synthesis of most proinflammatory cytokines is tightly regulated at the level of gene transcription, and they often induce the synthesis of other cytokines that act in an allosteric manner to suppress their synthesis. With the recent explosion in the number of identified cytokines, it is recognized that cytokines can rarely be classified according to their biological function. Rather, most cytokines have overlapping, pleiotropic biologic activities, dependent on what other cytokines and mediators are present in the milieu at that time. What is generally agreed on, however, is that cytokines are protein messengers that convey information among and within cells via specific receptor molecules. Furthermore, cytokines signal to immune and somatic tissues the presence of inflammation, and in doing so, regulate key components of the innate and acquired immune responses. Cytokine signaling can occur in an endocrine, paracrine, autocrine, and juxtacrine fashion, dependent on the cytokine and the current environment in which the cytokine is produced. This is an important consideration when attempting to measure cytokines in biologic fluids, such as the blood, bronchoalveolar lavage, or cerebrospinal fluid.