RS 09 TFA is a TLR4 agonist. RS 09 TFA promotes NF-κB nuclear translocation and induces inflammatory cytokine secretion in RAW264.7 macrophages in vitro. RS 09 TFA acts as an adjuvant in vivo; RS 09 TFA enhances X-15 specific antibody serum concentrations, when administered with X-15-KLH in mice.