HMGB1 is a nuclear chromatin-associated protein and, in addition to its intracellular role, it can also act (but possibly not other HMGB proteins) as a signaling molecule (cytokine) upon release into the extracellular environment by necrotic, inflammatory and even apoptotic cells (reviewed by Štros, 2010), promoting cytokine expression, recruitment of inflammatory cells, and cell migration and/or proliferation. The cytokine activities of HMGB1 are manifested via interaction of secreted HMGB1 with several surface molecules including the RAGE, Toll-like receptors 2 and 4, thrombomodulin and syndecan. Naturally acquired anti-HMGB1 antibodies are produced during septic shock and their presence is associated with higher severity scores. HMGB1 can also form complexes with exogenous agents (endotoxin, microbial DNA) or endogenous molecules (IL-1beta, nucleosomes) which increase the capacity of HMGB1 for activation of adaptive and innate immunity. These complexes induce formation of autoantibodies against HMGB1 in serum, and early detection of these antibodies (as well as HMGB1) is important for diagnostics and efficacy of treatment of numerous diseases such as rheumatic diseases (arthritis and systematic lupus erythematosus), pancreatitis, respiratory disorders, hemorrhagic shock and viral diseases such as HIV [Štros, M, 2010; Andersson and Harris, 2010]. The aim of the Bc. thesis is to review current literature on HMGB1 release (as well as anti-HMGB1 presence) in serum in connection with diagnosis of several illnesses. References: Štros, M. (2010) Biochim. Biophys. Acta 1799:101-113 Anderson, U, and Harris, H.E. (2010) Biochim. Biophys. Acta 1799:141-148