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Evidence-Based Complementary and Alternative Medicine
Volume 2013, Article ID 635960, 6 pages
Research Article

A Single-Center, Randomized Double-Blind Placebo-Controlled Study Evaluating the Effects of Poly-Gamma-Glutamate on Human NK Cell Activity after an 8-Week Oral Administration in Healthy Volunteers

1Department of Family Medicine, Seoul St. Mary's Hospital, The Catholic University, Seoul 137-701, Republic of Korea
2Viral Infectious Disease Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 305-806, Republic of Korea
3Clinical Trials Center, Department of Pharmacology, College of Medicine, Chungnam National University, Daejeon 301-721, Republic of Korea
4Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA
5Department of Advanced Fermentation Fusion, Kookmin University, Seoul 136-702, Republic of Korea
6BioLeaders Corporation, Daejeon 305-500, Republic of Korea
7Infection and Immunity Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahak-ro, Yuseong-gu, Daejeon 305-806, Republic of Korea

Received 30 October 2013; Accepted 13 November 2013

Academic Editor: Jae Youl Cho

Copyright © 2013 Kyung-Soo Kim et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A randomized double-blind placebo-controlled immunity study involving 99 healthy volunteers was performed to investigate the effect of poly-γ-glutamate (γ-PGA) on human natural killer (NK) cell activity in peripheral blood. The volunteers were randomly assigned to one of three groups and orally treated with solutions (25 mL) containing 0 mg (placebo), 250 mg (low dosage), or 500 mg (high dosage) of γ-PGA. Each volunteer took one dose every 12 hours for 8 weeks. Blood samples were drawn before the initial treatment and at the 4th and the 8th weeks of treatment. NK cell activity was assessed by measuring its degranulation, cytokine production, and cytotoxicity against the K562 cell line. Our results revealed that the cytotoxic activities of NK cells from the high-dosage γ-PGA group were significantly higher ( for all comparisons) compared to the low dosage and placebo groups at weeks 4 and 8 after the initial treatment. This increase in the NK cell activity among peripheral blood mononuclear cells (PBMCs) of healthy individuals was also confirmed in vitro (as assessed by the degranulation and cytokine production). These results suggest that the oral administration of γ-PGA induces a cell-mediated immunity by increasing the NK cell activity in humans.