Immuno-Enhancing Effects and Minimum Effective Dose of the Co-Extracted Herbal Formulation JI-HK601 via NK Cell Activation

immune function analyses in mice. To assess safety, both extracts were administered orally at a dose of 400 mg/kg for 14 consecutive days. Measurements of body weight, spleen index, and peripheral blood cell profiles revealed no significant differences compared to the normal control group, suggesting that neither extract induced systemic toxicity or abnormal immune organ responses under the tested conditions. Immunological assessments indicated that JI-HK601 enhanced natural killer (NK) cell cytotoxic activity to a greater extent than IEM, suggesting a greater functional improvement in NK cell responsiveness. In subsequent dose-response studies of JI-HK601, no toxicity was observed at any dose, whereas increases in T-cell proportion and NK cell activity were noted at 400 mg/kg. Analysis of T-cell transcription factors showed selective upregulation of T-box transcription factor 21 (T-bet), a key regulator of T helper type 1 (Th1) differentiation. These results indicate that JI-HK601 preferentially stimulates Th1-associated immune pathways while enhancing innate cytotoxic function. Overall, the findings demonstrate that JI-HK601 strengthens NK cell activity and promotes Th1-related cellular immunity while maintaining a favorable safety profile across the evaluated dose range. Thus, these results provide foundational data for assessing the potential use of JI-HK601 as an immune-enhancing ingredient in functional foods and complementary and alternative medicine.