Doctoral Thesis / Dissertation from the year 2014 in the subject Medicine - Biomedical Engineering, Cairo University (Faculty of Science), course: Immunology, language: English, abstract: P. aeruginosa is a gram-negative bacterium that causes a variety of diseases in compromised hosts. Bacterial endotoxins such as LPS are the major outer surface membrane components present in almost all gram-negative bacteria and act as extremely strong stimulators of innate immunity and inflammation of the airway. The present study was undertaken to determine the effect of combined administration of Gentamicin (GENT) as antibiotic and Dexamethasone (DEXA) as ant-inflammatory drug on some physiological, immunological and histological parameters. After determination of LD50 of P. aeruginosa, mice groups were injected with DEXA, GENT and LPS alone or in combination. LPS single injection caused a significant increase of total protein, globulin, total leukocyte count, lymphocytes, neutrophils and level of IgM and IgG. DEXA induced an increase of serum total lipid, ALT and AST levels, neutrophilia and lymphopenia. GENT administration increased serum total protein, globulin, total lipid, ALT and AST levels. Physiological and immunological examination demonstrated that combined treatment has a significant effect as decreaseing serum total protein, globulin, lymphocytes and IgG level than single treatment. Histological examination demonstrated that the inflammation of thymus, spleen, lymph node and liver decreases in mice received combined treatment than those received individual treatment. Concurrent administration of DEXA and GENT has greatest effect in protecting organs against damage in case of endotoximia.