4. Discussion
A/H1N1, gastrointestinal tract
INFLUENZA
Intake of BB536 reportedly enhanced the immune response by maintaining NK activity and increasing IgA in serum in hospitalized elderly patients with enteral nutrition. BB536 supplementation also elevated the acquired immune response by increasing the antibody titer after A/H1N1 influenza vaccination [Of the gut immune cells, pDCs play a crucial role in defending the gastrointestinal tract against pathogens and maintaining host immune homeostasis [Additionally, 4 h of cocultivation with hk-BB536 resulted in a significant increase in the expression level of In previous studies, live BB536 bacteria highly induced the amount of IFNγ cocultivated with human PBMCs for 24 h [On the other hand, regarding the effects of BB536 on the level of the innate immune response, no obvious changes were detected in neutrophil phagocytic or bactericidal activities (One limitation of this clinical study might be that significant fluctuations in immune-related clinical outcomes were difficult to observe because of the strong effects of protective measures taken during the COVID-19 pandemic and because their immune levels at baseline were within the normal range. Furthermore, the dosage and intervention period should also be explored further, and additional clinical studies without mask wearing are needed.