Efficacy of Lactococcus lactis 11/19-B1 in a Mouse Model of Allergic Rhinitis.

INTRODUCTION: Lactococcus lactis (L. lactis) is widely used in fermented foods and has immunomodulatory properties. However, its effects on allergic rhinitis remain unclear. OBJECTIVE: This study evaluated the efficacy of L. lactis 11/19-B1 in mitigating allergic rhinitis symptoms in a mouse model. METHODS: Female BALB/c mice were fed a diet supplemented with heat-killed L. lactis 11/19-B1, while allergic rhinitis was induced via intraperitoneal and intranasal administration of ovalbumin (OVA). The positive control group received a standard diet without L. lactis 11/19-B1. Sneezing frequency was recorded, and tissue samples were collected for analysis. Serum OVA-immunoglobulin E (IgE) levels were also measured, nasal mucosa histopathology assessed, and the interleukin 4 (IL-4), interferon gamma (IFN-γ), T helper (Th) 1/Th2 balance in cluster of differentiation (CD) 4+ T cells analyzed by flow cytometry (FCM). RESULTS: Mice receiving L. lactis 11/19-B1 showed significantly reduced sneezing frequency and decreased eosinophil infiltration in the nasal mucosa. No significant changes in serum OVA-IgE levels were observed. Flow cytometry analysis showed a significant increase in the Th1/Th2 ratio in Peyer's patches in the L. lactis 11/19-B1 group compared with the positive control group. CONCLUSION: These findings suggest that L. lactis 11/19-B1 alleviates allergic rhinitis symptoms by modulating the Th1/Th2 balance and reducing eosinophil infiltration, independently of IgE suppression. These findings highlight its potential as a dietary supplement for allergic disease management .