Omp19 co-administered as adjuvant induces antigen cross- presentation and triggers CD8 T cells responses in vivo.

CORIA, LORENA; IBANEZ, ANDRES; DELPINO, MARIA VICTORI; BERGUER, PAULA; BARRIONUEVO, PAULA; GIAMBARTALOMEI, GUILLERMO; CASSATARO, JULIANA.

Seattle, Washington.USA

Congreso; Immunological Mechanisms of Vaccination (S1)* *Part of the Keystone Symposia Global Health Series, Supported by the Bill & Melinda Gates Foundation** October 27 - November 1, 2010. Seattle, Washington.USA.; 2010

In previous studies we have shown that Omp19 from Brucella spp. as adjuvant induces CD4+ T cell responses. In this study, we evaluated the adjuvant capacity on CD8+ T cell responses using chicken ovoalbumin (OVA) as antigen (Ag) model. Omp19 co-administered with OVA induces OT-I cell proliferation in vivo and IFN-g producing T CD8 cells. These results suggest that Omp19 co-administered as adjuvant facilitates antigen cross-presentation inducing the activation of CD8+ T cells. We further investigated if dendritic cells (DCs) are involved in the ability of Omp19 to stimulate this response. A higher percentage of IFN-g producing T CD8 and cytotoxic T cells was induced when purified DCs were previously stimulated with OVA+Omp19 compared to T cells co-cultivated with DCs pulsed with OVA alone. These results suggested that Omp19 can act directly on DCs to enhance T cell responses. Therefore, we evaluated if Omp19 has a direct effect on DCs that could enhance the Ag internalization and presentation to T cells. DCs pulsed with OVA-FITC+Omp19 showed an increase in Ag internalization compared with OVA-FITC alone. These results indicate that Omp19 increases the Ag capture by immature DCs in vitro. In conclusion, Omp19 as adjuvant increases the amount of internalized Ag in DCs. This capacity would lead the improved T CD8 and CTL immune responses observed when Omp19 is co-administered with the Ag. This work was supported by grants from: Bill & Melinda Gates Foundation through the Grand Challenges Explorations Initiative, from the Agencia Nacional de Promocion Cientifica y Tecnologica (ANPCyT-Argentina) and from University of Buenos Aires.