Brucella abortus RNA inhibits the expression of Major Histocompatibility Complex Class I (MHC-I) molecules in human monocytes

MILILLO, M. AYELÉN; VELASQUEZ, LIS N.; DELPINO, VICTORIA; GIAMBARTOLOMEI, GUILLERMO; BARRIONUEVO, PAULA

Mar del Plata, Buenos Aires

Congreso; LIX Reunión Científica Anual de la Sociedad Argentina de Investigación Clínica (SAIC). LXII Reunión Anual de la Sociedad Argentina de Inmunología (SAI).; 2014

Sociedad argentina de Investigación Clínica-Sociedad Argentina de Inmunología

Brucella abortus elicits a vigorous Th1 immune response which activates cytotoxic T lymphocytes. However, B. abortus is able to persist inside its host and establishes a chronic infection. We recently reported that infection of human monocytes/macrophages with B. abortus inhibits the IFN-γ-induced MHC-I cell surface expression down-modulating cytotoxic CD8+ T cell responses. MHC-I down-modulation depends on bacterial viability and results from the capacity of B. abortus to retain the MHC-I molecules within the Golgi apparatus. However, the components of B. abortus involved in this phenomenon remained unknown. Prokaryotic RNA has been recently characterized as a special class of viability-associated PAMPs (vita-PAMPs). Thus, the aim of this study was to evaluate the effect of B. abortus RNA on IFN-γ-induced MHC-I expression. For this, human monocytic THP-1 cells were incubated with B. abortus RNA (0.1-20 µg/ml) in the presence of IFN-γ for 48 h. The expression of MHC-I molecules (HLA-ABC) was then evaluated by flow cytometry. B. abortus RNA significantly (p