B. ABORTUS DOWN-REGULATES MAJOR HISTOCOMPATIBILITY COMPLEX (MHC) CLASS II MATURE AND IMMATURE MOLECULES BY INHIBITION OF CLASS II TRANSACTIVATOR GENE EXPRESSION

VELÁSQUEZ, LIS NOELIA; DELPINO, M. VICTORIA; FERNANDEZ, PABLO M.; GIAMBARTOLOMEI, GUILLERMO H.; BARRIONUEVO, PAULA

Los Cocos, Cordoba

Congreso; LXI Reunión Anual de la Sociedad Argentina de Inmunología; 2013

Brucella abortus is an intracellular pathogen capable of surviving inside macrophages and establishing a chronic infection. In order to survive inside the host, this bacterium must trigger different strategies to evade the robust adaptive CD4+ T cell response it elicits. Previously we demonstrated that B. abortus inhibits the IFN-γ-induced surface expression of MHC-II molecules on human monocytes. This phenomenon was mediated by B. abortus outer membrane lipoproteins and through the secretion of IL-6. Moreover, this diminished expression of MHC-II molecules correlated with a reduction in antigen presentation. However, the molecular mechanism by which B. abortus is able to down-regulate the expression of MHC-II molecules remained to be elucidated. In this study, we demonstrated that infection with B. abortus inhibits the IFN-γ-induced transcription of the class II transactivator (CIITA) (p