ADJUVANT FORMULATION BASED ON AN ASCORBYL PALMITATE NANOSTRUCTURE AND CPG-ODN ENHANCES IFN-g+ T CELL RESPONSE AND ANTIBODY AVIDITY

ANA CHIODETTI; FERNANDA SÁNCHEZ-VALLECILLO; GABRIELA ULLIO; MARÍA I CRESPO; GABRIEL MORÓN; SANTIAGO PALMA; MARÍA C. PISTORESI-PALENCIA; DANIEL ALLEMANDI; BELKYS A. MALETTO

Los Cocos

Congreso; LXI Reunión Anual de la Sociedad Argentina de Inmunología; 2013

Sociedad Argentina de Inmunología

Previously we have shown that CpG-ODN formulated in a 6-O-ascorbyl palmitate nanostructure (Coa-ASC16) was more efficient as adjuvant than CpG-ODN solution using OVA as an antigen model. Particularly, immunization of mice with OVA/CpG-ODN/Coa-ASC16 resulted in a significant increase of OVA-specific antibody titers and kinetics of apparition (IgG, IgG1, and IgG2a) and IFN-γ and IL-17 secretion compared with OVA/CpG-ODN immunized mice. In order to evaluate the quality of the immune response induced by this adjuvant strategy, we determined the frequency of IFN-γ+ T cells (intracellular staining and flow cytometry) and the binding avidity of plasma antibodies (IgG) for OVA (KSCN elution assay). Mice were subcutaneously immunizated on days 0, 7 and 14 with OVA/CpG-ODN/Coa-ASC16 or OVA/CpG-ODN (dose/mice: OVA:60μg, CpG-ODN:75 μg). On day 21, mice were sacrificed and plasma and spleen were obtained. Spleen cell suspensions were cultured with medium or OVA (100μg/ml). We observed that splenocytes from mice immunized with OVA/CpG-ODN/Coa-ASC16 presented a higher frequency of OVA-specific IFN-γ-producing CD4+ (0.60±0.40 vs 4.60±0.04) and CD8+ (1.9±1.0 vs 5.5±0.7) T cells than splenocytes from mice immunized with OVA/CpG-ODN (p<0.05). For the determination of antibody avidity the approach was elution of bound IgG with increasing concentrations of KSCN (0-3M). IgG from mice immunized with OVA/CpG-ODN/Coa-ASC16 was more resistance to KSCN elution at 0.5, 1.0, and 1.5M KSCN (89±6, 80±6, and 65±8 %OD490, respectively) than mice immunized with OVA/CpG-ODN (68±4, 35±3 and 15±3 %OD490, respectively) (OD490 in the KSCN-treated wells were expressed as a percentage of the reference well not treated with KSCN) (p<0.05). Our results show that this adjuvant strategy improves both OVA-specific CD4+ and CD8+ T cell response and generate higher avidity specific antibodies than CpG-ODN alone, demonstrating the potentiality of this strategy as a new adjuvant option for future vaccines.