Characterization of cytotoxic CD8+ T lymphocyte (CTL) effector and memory response induced by a novel formulation strategy for the CPG-ODN adjuvant using a nanostructure platform

CHIODETTI, A; SANCHEZ-VALLECILLI, MF; AGUIRRE,MV; PALMA SD; ALLEMANDI, D; MORÓN, G; PISTORESI, MC; MALETTO, B

Buenos Aires

Congreso; LXIII Reunión de la Sociedad Argentina de Inmunología; 2015

Sociedad Argentina de Inmunología

Abstract: Background: Previously, we have shown that CpG-ODN formulated with a nanostructure of 6-O-ascorbyl palmitate (Coa-ASC16) has the capacity to enhance a specific humoral and cellular (CTL and Th1) immune response in compare to the CpG-ODN solution alone using OVA as an antigen model. In addition, Coa-ASC16 alone elicited IL-6 production. Here, we farther characterized the CTL response and the possible signals involved on its development. Methods: To study effector characteristics of CD8+ T lymphocytes, mice were subcutaneously immunized on day 0 with OVA/CpG-ODN/Coa-ASC16 or OVA/CpG-ODN. Seven days after immunization, spleen cell suspensions were cultured with medium or OVA257?264 (1 μg/ml) for intracellular staining. To test an effector memory CTL response, we performed an in vivo cytotoxicity assay 30 days after immunization with OVA/CpG/Coa-ASC16. To seek if the CTL response was IL-6 dependent we repeat the assay in Il-6-/- mice. Results: Mice immunized with OVA/CpG-ODN/Coa-ASC16 presented a higher frequency of CD8+ T lymphocytes producing pro-inflamatory cytokines IFN-γ (0.53±0.11 vs 0.05±0.02; p<0.01) and TNF-α (0.25±0.03 vs 0.04±0.03; p<0.01), and expressing LAMP-2 cell surface protein (0.54±0.01 vs 0.11±0.11; p<0.05) after stimulation with OVA257-264 peptide than splenocytes from mice immunized with OVA/CpG-ODN. The CTL response persisted for at least 30 days after immunization with OVA/CpG/Coa-ASC16 (% specific killing: 63±26). Il6-/- mice showed CTL response as efficiently as in WT mice. Conclusions: OVA/CpG-ODN/Coa-ASC16 exhibited a robust capacity to induce a specific-antigen CTL response that is IL-6 independent. This adjuvant strategy represents an attractive approach for the design of effective vaccines against intracellular pathogens.