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

MILILLO MA; VELÁSQUEZ LN; TROTTA A; DELPINO MV; BALBOA L; GIAMBARTOLOMEI GH; BARRIONUEVO P

Mar del Plata

Congreso; LXIV Reunión Anual de la Sociedad Argentina de Inmunología (SAI).; 2016

Sociedad Argentina de Inmunología

Brucella abortus elicits a strong Th1 immune response which activates cytotoxic T lymphocytes. However, this pathogen is able to survive inside macrophages and generate a chronic infection. Previously we reported that infection of human monocytes/macrophages with B. abortus inhibits the IFN-γ-induced MHC-I cell surface expression. More importantly, we have recently demonstrated that 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 the component, signalling pathways and mechanisms implicated in MHC-I down-modulation. For this, RNases-treated B. abortus RNA was employed to stimulate human monocytic THP-1 cells in the presence of IFN-γ for 48 h. Then, the expression of MHC-I molecules was evaluated by flow cytometry. Surprisingly, completely degraded RNA was still able to inhibit MHC-I expression (p