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

CORIA LM, AE IBÁÑEZ, KA PASQUEVICH, P BERGUER, GH GIAMBARTOLOMEI Y J. CASSATARO.

Congreso; 6th International Research Conference on Brucellosis. Buenos Aires.; 2011

In previous studies we have shown that the protein moiety of Omp19 from Brucella spp.(U-Omp19) 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. We observed that U-Omp19 co-administered with OVA increases OT-I cell proliferation in vivo and IFN-ã producing CD8+ T cells in comparison with the administration of OVA alone. These results indicate that Omp19 co-administered as adjuvant facilitates antigen cross-presentation inducing the activation of CD8+ T cells. Given the capacity of antigen presenting cells (APCs) to induce adaptive immune responses, we investigated if APCs are involved in the ability of U-Omp19 to stimulate a specific CD8+ T cell response. To assess this, purified dendritic cells (DCs) from spleen of C57BL/6 mice were treated with OVA alone or U-Omp19 or LPS as positive control and then co-cultivated with OTI CD8+ T cells. Then, the induction of IFN-ã producing T cells by intracellular IFN-ã staining and degranulation of cytotoxic T cells by CD107a expression on the membrane were evaluated. A higher percentage of IFN-ã producing CD8+ and cytotoxic T cells was induced when DCs were stimulated previously with OVA+U-Omp19 compared to T cells co-cultivated with DCs pulsed with OVA. Next, we evaluated if Omp19 has an effect on Ag internalization by APCs. To this end, DCs purified from mouse spleens were pulsed in vitro with OVA-FITC alone or OVA-FITC plus U-Omp19 or LPS as positive control. DCs pulsed with OVA-FITC+U-Omp19 showed an increase in Ag internalization compared with OVA alone. We have also found that U-Omp19 increased OVA internalization by J774 macrophage and by A20J B-lymphoma cell lines at different times. These results indicate that U-Omp19 increases the Ag uptake by immature DCs, macrophages and B lymphocytes in vitro. This capacity would lead the improved CD8+ and CTLs immune responses observed when U-Omp19 is co-administered with the soluble Ag.Brucella spp.(U-Omp19) 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. We observed that U-Omp19 co-administered with OVA increases OT-I cell proliferation in vivo and IFN-ã producing CD8+ T cells in comparison with the administration of OVA alone. These results indicate that Omp19 co-administered as adjuvant facilitates antigen cross-presentation inducing the activation of CD8+ T cells. Given the capacity of antigen presenting cells (APCs) to induce adaptive immune responses, we investigated if APCs are involved in the ability of U-Omp19 to stimulate a specific CD8+ T cell response. To assess this, purified dendritic cells (DCs) from spleen of C57BL/6 mice were treated with OVA alone or U-Omp19 or LPS as positive control and then co-cultivated with OTI CD8+ T cells. Then, the induction of IFN-ã producing T cells by intracellular IFN-ã staining and degranulation of cytotoxic T cells by CD107a expression on the membrane were evaluated. A higher percentage of IFN-ã producing CD8+ and cytotoxic T cells was induced when DCs were stimulated previously with OVA+U-Omp19 compared to T cells co-cultivated with DCs pulsed with OVA. Next, we evaluated if Omp19 has an effect on Ag internalization by APCs. To this end, DCs purified from mouse spleens were pulsed in vitro with OVA-FITC alone or OVA-FITC plus U-Omp19 or LPS as positive control. DCs pulsed with OVA-FITC+U-Omp19 showed an increase in Ag internalization compared with OVA alone. We have also found that U-Omp19 increased OVA internalization by J774 macrophage and by A20J B-lymphoma cell lines at different times. These results indicate that U-Omp19 increases the Ag uptake by immature DCs, macrophages and B lymphocytes in vitro. This capacity would lead the improved CD8+ and CTLs immune responses observed when U-Omp19 is co-administered with the soluble Ag.