Mechanisms of Immunostimulants in Regulating IFN-γ and IL-6 during inflammatory responses and immune modulation: Implications for therapeutic and vaccine development

Background: Immunostimulants are natural or synthetic agents that enhance host immune responses through the activation of innate and adaptive immune mechanisms. They are widely utilized in human and veterinary medicine as vaccine adjuvants, immunotherapeutic agents, and prophylactic interventions against infectious diseases. Their immunomodulatory effects are primarily mediated through cytokine networks, among which interferon-gamma (IFN-γ) and interleukin-6 (IL-6) play pivotal roles in regulating inflammation, pathogen clearance, and immune homeostasis.
Objective: This review aims to comprehensively examine the molecular mechanisms by which immunostimulants regulate IFN-γ and IL-6 production and to discuss the implications of these cytokine responses in inflammation, immune modulation, vaccine development, and emerging therapeutic applications.
Methods: A narrative literature review was conducted by synthesizing current evidence from experimental, clinical, and translational studies investigating the interactions between immunostimulants and cytokine signaling pathways. Particular emphasis was placed on studies examining Toll-like receptor (TLR), NOD-like receptor (NLR), and cytosolic nucleic acid sensing pathways involved in IFN-γ and IL-6 regulation.
Results: The available evidence indicates that immunostimulants modulate IFN-γ and IL-6 production through multiple innate immune signaling pathways, including TLR-, NLR-, and cGAS-STING-mediated mechanisms. Activation of these pathways promotes antigen presentation, dendritic cell maturation, leukocyte recruitment, and adaptive immune priming. IFN-γ predominantly enhances cellular immunity through macrophage activation, Th1 polarization, and intracellular pathogen elimination, whereas IL-6 regulates acute-phase responses, B-cell maturation, T-cell differentiation, and tissue repair. The interplay between IFN-γ and IL-6 is highly context-dependent, exhibiting both synergistic and antagonistic effects that influence immune protection and inflammatory outcomes. Therapeutically, controlled induction of these cytokines has demonstrated significant potential for improving vaccine efficacy, enhancing cancer immunotherapy, and strengthening resistance against infectious diseases.
Conclusion: Immunostimulants exert their biological effects through complex interactions with innate immune receptors and downstream cytokine networks. The coordinated regulation of IFN-γ and IL-6 is a critical determinant of effective immune activation and inflammatory control. A deeper understanding of the molecular pathways governing these cytokines will facilitate the development of next-generation immunostimulants, precision vaccine adjuvants, and innovative immunotherapeutic strategies for both human and veterinary medicine.