CD137L adjuvanted vaccine increases antigen-specific T-cell responses but impacts antigen-specific humoral responses

CD137 engagement through CD137 ligand (CD137L) or agonistic antibodies has shown promising results in cancer immunotherapy. Here, we explored CD137L as an adjuvant to improve vaccine-induced T-cell mediated immunity. Here we show that including CD137L in an mRNA vaccine significantly boosted T-cell responses, but not in a protein vaccine. Furthermore, CD137L-containing vaccines induced lower antibody responses. These findings support that CD137L may boost the efficacy of T-cell-based mRNA vaccines.