B. abortus RNA a novel vita-pamp involved in the down-modulation of MHC-I expression on human monocytes.

LIS N. VELASQUEZ; LUCIANA BALBOA; ALDANA TROTTA; GUILLERMO H GIAMBARTOLOMEI; M. AYELEN MILILLO; M. VICTORIA DELPINO; PAULA BARRIONUEVO

Mar del Plata

Congreso; 63. LXIV Reunión Anual de la Sociedad Argentina de Inmunología (SAI). 15-19 Noviembre 2016; 2016

Brucella abortus elicits a strong Th1 immune response whichactivates cytotoxic T lymphocytes. However, this pathogen is ableto survive inside macrophages and generate a chronic infection.Previously we reported that infection of human monocytes/macrophageswith B. abortus inhibits the IFN-γ-induced MHC-I cellsurface expression. More importantly, we have recently demonstratedthat B. abortus RNA, described as a viability-associated(vita)-PAMP, is the bacterial component involved in this phenomenon.Thus, the aim of this study was to further characterize thecomponent, signalling pathways and mechanisms implicated inMHC-I down-modulation. For this, RNases-treated B. abortus RNAwas employed to stimulate human monocytic THP-1 cells in thepresence of IFN-γ for 48 h. Then, the expression of MHC-I moleculeswas evaluated by flow cytometry. Surprisingly, completelydegraded RNA was still able to inhibit MHC-I expression (p