36th International Symposium on Intensive Care and Emergency Medicine

Introduction: Intravenous(IV) immunoglobulin(Ig) treatment is known to alleviate behavioral deficits in the experimentally induced model of sepsis. To delineate the mechanisms by which IVIg treatment prevents neuronal dysfunction, an array of immunological and apoptosis markers was investigated. Methods: Sepsis was induced by cecal ligation perforation(CLP) in rats. The animals were divided into five groups; sham, control, CLP + saline, CLP + immunoglobulin G IgG(250 mg/kg,iv), and CLP + immunoglobulins enriched with immunoglobulin M-IgGAM(250 mg/kg,iv). Blood and brain samples were taken in two sets of experiments after CLP to see the early(24 hrs) and late(10 days) effects of treatment. Total complement activity, complement 3(C3) and soluble complement C5b-9 levels were measured in sera of rats using ELISA-based methods. Cerebral complement content was analyzed by Western Blot. Immune cell infiltration and gliosis were examined by immunohistochemistry using cluster of differentiation 3, CD4, CD8, CD11b, CD19 and glial fibrillary acidic protein antibodies. Apoptotic neuronal death was investigated by TUNEL staining and Western Blot-based semi-quantitative evaluation of brain homogenates by bax and bcl-2 antibodies. Results: IV IgG and IgGAM administration significantly reduced systemic complement activity but increased serum C3 and soluble C5b-9 levels. Likewise, Western Blot data showed slightly increased C5b-9 expression and significantly reduced C1q expression in brain samples of IgGAM-treated but not IgG-treated septic rats especially in the first day of administration. No cerebral cellular infiltrates were observed in treated and non-treated septic rats. By contrast, IV IgG and IgGAM treatment induced considerable amelioration in glial cell proliferation which was increased in non-treated rats. IgG and IgGAM treated rats exhibited significantly reduced numbers of apoptotic neurons and cerebral expression levels of bax and bcl-2 as compared to nontreated rats. Conclusions: We suggest that IV IgG and IgGAM administration ameliorates neuronal dysfunction and behavioral deficits by reducing apoptotic cell death and glial cell proliferation. IgGAM treatment might be suppressing classical complement pathway by reducing C1q expression.