247EXPRESSION AND RELEASE OF HIGH MOBILITY GROUP BOX 1 (HMGB1) PROTEIN BY MONONUCLEAR CELLS FOLLOWING SURGERY OR ANESTHESIAThis study investigated the kinetics of HMGB1 production and its relationship with IL-6 release following major elective surgery. A total of 94 patients undergoing major abdominal procedures were enrolled. Blood samples were collected at three time points: before surgery (t0), immediately after surgery (t1), and 24 hours post-surgery (t2). Monocytes were isolated using CD14 microbeads and analyzed for HMGB1 expression via flow cytometry, while serum HMGB1 and IL-6 levels were measured using Western blotting and ELISA, respectively. Results showed a significant increase in HMGB1 expression in monocytes at t1, accompanied by a notable rise in serum HMGB1 and IL-6 at t2. In vitro, monocytes treated with HMGB1 released IL-6, indicating a direct link between HMGB1 and IL-6 secretion. Additionally, decreased intracellular HMGB1 suggested translocation from the nucleus to the cytoplasm. These findings highlight the role of monocytes in HMGB1- mediated IL-6 release, contributing to the inflammatory response following surgical and anesthesia trauma.Rajesh@gmail.comResearch922019High mobility group box 1, neuro-endocrine-hormone flux, Stress response.Dr. RajeshAssistant Professor, Department of Anaesthesiology, Tagore Medical College and Hospital, Rathinamangalam, Melakottaiyur, Chennai – 600127, Tamil Nadu, India.