Guinea Pig Interleukin-6 (IL-6) is a multifunctional pro-inflammatory cytokine and a central member of the IL-6 cytokine family—including IL-6, IL-11, IL-27, IL-31, leukemia inhibitory factor (LIF), oncostatin M (OSM), ciliary neurotrophic factor (CNTF), cardiotrophin-1 (CT-1), and cardiotrophin-like cytokine factor 1 (CLCF1)—which signal through receptor complexes containing the shared gp130 subunit to activate JAK/STAT and MAPK pathways. In guinea pigs (Cavia porcellus), IL-6 plays a critical role in regulating acute-phase responses, fever, leukocyte recruitment, and B- and T-cell differentiation during infection and inflammation. Guinea pigs are widely used as translational models for human infectious diseases, including tuberculosis, influenza, cytomegalovirus, and hemorrhagic fevers, where IL-6 expression correlates with pulmonary inflammation, systemic immune activation, and disease severity. Dysregulated IL-6 production contributes to immunopathology and tissue damage, making it an important biomarker for monitoring infection progression and evaluating vaccine or therapeutic efficacy. In both laboratory animal health and biomedical research, characterization of guinea pig IL-6 and related cytokine family members supports studies of host-pathogen interactions, respiratory and systemic inflammatory responses, and comparative immunology, reinforcing the guinea pig’s value as a model for human infectious and inflammatory diseases.