Volatile anesthetics are major drugs to provide general anesthesia during perioperative period. While the primary purpose is to provide analgesia, hypnosis and immobility, they are suggested to possess immunomodulatory effects. Alternation of immune function by volatile anesthetics can be clinically significant particularly fr critical-ill patients. Candidate's long-term goal is 1) to elucidate the molecular mechanism and degree of immunomodulatory effects by various, clinically-used anesthetics, thereby providing clinicians the rational to use one anesthetic over others in the context of patient's underlying diseases, and 2) to redesign new anesthetics without immunomodulation. We focused our target on two adhesion molecules L2 and M2 that are expressed exclusively on leukocytes, playing a role in leukocyte arrest on the endothelium, phagocytosis, immunological synapse formation, natural killer cells cytotoxicity, and so on. In our preliminary experiments, we showed that L2 and M2 are functionally inhibited by isoflurane. Also L2, not M2 was inhibited by sevoflurane. We hypothesize that volatile anesthetics bind to these integrins and modify their functions, thereby modulating immune function. In this proposal, we will investigate how volatile anesthetics interact with these molecules structurally. Our proposed research consists of three Aims, and will be performed in Immune Disease Institute (Program in Cellular and Molecular Medicine in Children's Hospital Boston). In Aim1 and Aim 2, we will determine the interaction of clinically used anesthetics with L2 and M2 and their binding site(s). The effects of volatile anesthetics on ligand binding will be assessed in cell-free and cell-based assays using flow cytometery and V-bottom assay. The binding parameters will be measured with isothermal titration calorimetry. Anesthetic binding site(s) will be assessed in the combination of X ray crystallography and photoactivatable anesthetics. In Aim3, we will examine biological effects by volatile anesthetics resulting from the impairment of these adhesion molecules' function. We will use natural killer cells cytotoxicity assay, Fc receptor mediated neutrophil cytotoxicity and phagocytosis assay for this purpose. Subsequently, our experimental results will provide insight into the underlying mechanism of volatile anesthetics-induced immunomodulation.