Spleen Dendritic Cells From Old Mice Generate A Low Cytotoxic Response Against Ova In Young Hosts

ESTEFANÍA ZACCA; MARÍA INÉS CRESPO; BELKYS A. MALETTO; MARÍA C PISTORESI- PALENCIA.; GABRIEL MORÓN

Buenos Aires

Congreso; First French-Argentine Immunology Congress y LVIII Reunión Anual de la Sociedad Argentina de Inmunología.; 2010

Sociedad Argentina de Inmunología.

During aging, B and T cells manifest changes that affect their response to antigens (Ag). However, it is practically unknown how dendritic cells (DCs) could participate in these changes. Our previous findings show that in spleen of 18-20 month-old mice (old) there is a lower content of DCs, which have a lower capacity to activate young naïve CD8 T cells than DCs from 3 month-old (young) mice. In this work we analyzed the ability of DCs from old mice to elicit a CTL response in young mice, in order to analyze the ability of DCs independently of the alterations already reported for CD8 T cells during aging. We first analyzed the capacity from old mice to develop a CTL response in vivo. We immunized i.v young and old mice with 2.5x109 latex beads coupled to OVA + PolyU/DOTAP and 7 days later, CTL response was assessed by an in vivo assay. Immunized mice were injected i.v. with equal proportions of CFSE-labeled syngeneic spleen cell populations (a control cell population labeled with 0.5 µM CFSE and an OVA257-264 peptide-loaded cell population labeled with 3µM CFSE). One day after injection cytotoxicity was assessed by FACS analysis on total spleen cells. We found that old mice developed a significant lower CTL response against OVA than young mice (4.7±1.5 vs 84±10%, respectively, p<0.05). We also measured IFN-g secretion by ELISA in supernatants of spleen cells in vitro restimulated with OVA257-264 peptide. We found a lower IFN-γ production in splenocytes from old mice compared to the young ones (0.32±0.01 vs. 1.9±1.6 ng/mL, respectively, p<0.05). To investigate whether this lower capacity from old mice to develop a CTL response in vivo could be due to a lower capacity of DCs from old mice to prime a CTL response in vivo, we immunized iv young mice with 1x106 DCs purified from the spleen of young and old mice incubated with OVA+PolyU/DOTAP. Seven days later, an in vivo CTL assay by FACS was performed. We found that DCs from old mice have a diminished capacity to prime a CTL response, as we observed a lower percentage of specific lysis in old mice compared to the young ones (41±23 vs. 89±13%, respectively, p<0.05). Altogether, the impairment in the generation of effective cytotoxic response against OVA that we observed in aged C57BL/6 is explained, at least in part, by a lower capacity of DCs to induce CTLs after immunization.