title: Agrobacteriumsp.-derived β-1,3-glucan enhances natural killer cell activity in healthy adults: a randomized, double-blind, placebo-controlled, parallel-group study.
abstract: OBJECTIVE
  The present study investigated the hypothesis that a highly pure linear β-1,3-glucan produced byAgrobacteriumsp. R259 enhances human natural killer (NK) cell activity and suppresses pro-inflammatory cytokines.
  
  
  METHODS
  In an eight-week, double-blind, randomized, placebo-controlled clinical trial, 83 healthy adults with white blood cell counts of 4,000-8,000 cells/µL were participated and randomly assigned to take two capsules per day containing either 350 mg β-1,3-glucan or placebo. Six participants withdrew their study consent or were excluded due to NK cell activity levels outside the normal range. NK cell activity and serum levels of immunoglobulin G (IgG) and cytokines, such as interferon (IFN)-γ, interleukin (IL)-2, IL-4, IL-6, IL-10, IL-12 and tumor necrosis factor (TNF)-α were measured.
  
  
  RESULTS
  NK cell activity and the serum levels of IL-10 were significantly higher from baseline to week 8 in the β-glucan group compared with the placebo group (P= 0.048,P= 0.029). Consumption of β-1,3-glucan also significantly increased NK cell activity compared with placebo after adjusting for smoking and stress status (P= 0.009). In particular, the effect of β-1,3-glucan on NK cell activity was greater in participants with severe stress than in those experiencing mild stress. However, the administration β-1,3-glucan did not significantly modulate the levels of IFN-γ, IL-2, IL-4, IL-6, IL-12, TNF-α and IgG compared with the placebo.
  
  
  CONCLUSIONS
  The results showed that supplementation with bacterial β-1,3-glucan significantly increased NK cell activity without causing any adverse effects. Additionally, the beneficial effect of β-1,3-glucan on NK cell activity was greater in participants experiencing severe stress.
authors.affiliation: Department of Food and Nutrition, Hanyang University, Wangsimni-ro 222, Seongdong-gu, Seoul 04763, Korea.
authors.forename: Yeon Joo
authors.initials: YJ
authors.lastname: Lee
authors.affiliation: Department of Anatomy and Cell Biology, College of Medicine, Hanyang University, Seoul 04763, Korea.
authors.forename: Doo-Jin
authors.initials: DJ
authors.lastname: Paik
authors.affiliation: Devision of Strategic Food Research, Korea Food Research Institute, Seongnam-si, Gyeonggi 13539, Korea.
authors.forename: Dae Young
authors.initials: DY
authors.lastname: Kwon
authors.affiliation: Devision of Strategic Food Research, Korea Food Research Institute, Seongnam-si, Gyeonggi 13539, Korea.
authors.forename: Hye Jeong
authors.initials: HJ
authors.lastname: Yang
authors.affiliation: Department of Food and Nutrition, Hanyang University, Wangsimni-ro 222, Seongdong-gu, Seoul 04763, Korea.
authors.forename: Yongsoon
authors.initials: Y
authors.lastname: Park
keywords: Glucans; clinical trial; cytokines; interleukin-10; natural killer cells