Keywords: Porcine reproductive and respiratory syndrome virus, baculovirus surface display vectors, neutralizing antibody, IFN-γ, IL-4.

Lidocaine, a commonly used local anesthetic, has demonstrated modulatory effects in various cells. This study investigates the impact of lidocaine on cytokine production in peripheral blood mononuclear cells (PBMCs) from healthy donors and tumor-infiltrating immune cells (TIICs) from gastric cancer patients. Flow cytometry and cytokine assays revealed that lidocaine inhibited IFN-γ and IL-12 production in CD8+ and CD14+ PBMCs, respectively, while enhancing anti-inflammatory cytokines IL-10, TGF-β, and IL-35 in CD4+CD25+ and CD14+ PBMCs. In contrast, lidocaine promoted the secretion of pro-inflammatory IFN-γ and IL-12 in CD8+ and CD14+ TIICs, while reducing IL-10, TGF-β, and IL-35 levels, thus shifting CD14+ macrophages toward an M1-like phenotype. Additionally, lidocaine decreased PD-1 expression and increased IFN-γ production in CD8+ TIICs via NF-κB activation, enhancing their cytotoxicity against primary gastric cancer cells (PGCCs). Importantly, lidocaine did not affect the viability of normal PBMCs, TIICs, or PGCCs at concentrations up to 1.5 mM. These findings suggest that lidocaine reprograms the tumor immune microenvironment, supporting its potential as an adjunct therapy in gastric cancer by enhancing anti-tumor immunity.