Screening of adjuvant for PD-L1 vaccine based on nitrated T cell epitope

To enhance the anti-tumor activity of tumor vaccine targeting PD-L1 based on the nitrated T-epitope (PD-L1-NitraTh), this research compared several adjuvants with different mechanisms to screen out the adjuvant most suitable for PD-L1-NitraTh. The results showed that Poly(I:C), CPG1018, swollen knotted polysaccharide SGP2 and GM-CSF could enhance the immunogenicity of PD-L1-NitraTh when used as adjuvants, with the Poly(I:C) group inducing the highest antibody titer. The results of qPCR for T cell differentiation-related cytokines showed that Poly(I:C) reduced the expression of GATA3 and FoxP3, indicating a strong effect on CD4⁺ T cell differentiation. Besides, compared with other adjuvants, Poly(I:C) could assist PD-L1-NitraTh to increase the infiltration of T cells as well as CD11b⁺ cells within tumor, suggesting that Poly(I:C) may be the suitable adjuvant for tumor vaccines based on the nitrated T epitopes.