Induces Two Types of Dendritic Cell Activation and Effectively Suppresses Onset of the Common Cold: A Randomized, Double-Blind, Placebo-Controlled Trial.

BACKGROUND/OBJECTIVES: GCL1815 is a lactic acid bacterium thought to activate dendritic cells. This randomized, placebo-controlled, double-blind study aimed to evaluate the effects of GCL1815 on human dendritic cells and the onset of the common cold.

METHODS

Two hundred participants were divided into two groups and took capsules containing either six billion GCL1815 cells or placebo for 8 weeks.

RESULTS

In the GCL1815 group, the cumulative incidence days of symptoms such as feverishness, fatigue, tiredness, runny nose, nasal congestion, and phlegm were significantly lower than in the placebo group. Moreover, the change in the expression of HLA-DR on plasmacytoid dendritic cells was significantly higher in the GCL1815 group than in the placebo group at 4 and 8 weeks of intake. The expression of CD86 on plasmacytoid dendritic cells was significantly increased in the GCL1815 group at 4 and 8 weeks compared with before intake. Additionally, the expression of HLA-DR on type 1 conventional dendritic cells was significantly higher in the GCL1815 group than in the placebo group at 8 weeks of intake. The expression of CD86 on type 1 conventional dendritic cells significantly decreased in the placebo group but remained statistically the same in the GCL1815 group after intake compared with before.

CONCLUSIONS

These results suggest that GCL1815 intake may enhance the response to viruses by activating two types of dendritic cells, thereby preventing the onset of systemic and local common colds in healthy adults.