Cotransfection of DC with TLR4 and MART-1 RNA induces MART-1-specific responses.
BACKGROUND: Cotransfection of dendritic cells (DC) with MART-1 and constitutively active TLR4 (caTLR4) RNA enhances the maturation of DC. MATERIALS AND METHODS: Immature DC were cotransfected with RNA constructs encoding MART-1 and caTLR4, and CTL responses were analyzed. RESULTS: Cotransfection of DC with MART-1 + caTLR4 enhanced the expression of CD80 and CD83 surface markers and increased the secretion of cytokines IL-6, IL-12, and TNFalpha. Neither the native nor the A27L-modified MART-1 RNA could induce significant DC maturation or cytokine secretion. More importantly, DC cotransfected with caTLR4 + MART-1 RNA induced MART-1-specific CTL responses of a higher magnitude than DC transfected with either the native or A27L MART-1 RNA. When the MART-1 RNA-transfected DC were treated with DC-maturing cytokines, the induced CTL were less frequent and less lytic than those induced with MART-1 + caTLR4. A 2- to 100-fold increase in MART-1 tetramer+ cells and 2- to 10-fold increases in IFNgamma secretion and cytotoxicity were seen in CTL induced with MART-1 + caTLR4 compared to CTL induced with either MART-1 or A27L RNA. CTL induced with the mixed RNA displayed high percentages of CD8+ cells coexpressing CD45RA, CD56, and 2B4 antigens. Transfection with caTLR4 alone induced DC maturation, but did not induce lytic CTL, suggesting that CTL responses were induced solely by MART-1 epitopes. CONCLUSIONS: caTLR4 increases the CTL-inducing capacity of DC generating a lytic response specific for the accompanying antigen. These results demonstrate the possibility of enhancing the immunogenicity of the native MART-1 and other RNA derived from weakly immunogenic tumors in DC-based immunotherapy.
Abdel-Wahab, Z; Cisco, R; Dannull, J; Ueno, T; Abdel-Wahab, O; Kalady, MF; Onaitis, MW; Tyler, DS; Pruitt, SK
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