A randomized double-blind placebo-controlled immunity study involving 99 healthy volunteers was performed to investigate the effect of poly-
Poly-
The effects of
Healthy volunteers (≥20 years) who met the selection criteria and were not on any therapy for physical or mental illnesses were enrolled in accordance with the guidelines of the Declaration of Helsinki. Approval was obtained from the institutional review boards of the Catholic University of Korea, College of Medicine (IRB approval number, KC10HSSI0064). Of the 102 participants, 99 met the trial criteria and were enrolled in the study. The study participants were randomized to three groups: 33 subjects (high-dosage) received 500 mg of
PBMCs were isolated from heparinized venous blood samples using Ficoll-Hypaque density gradient centrifugation according to standard procedures [
The human erythroleukemia cell line, K562, was cultured in RPMI 1640 (Invitrogen-Gibco) supplemented with 10% (vol/vol) heat-inactivated FBS, penicillin (50 units/mL) and streptomycin (50
The cytotoxic activity of NK cells against K562 cells, an NK cell-sensitive target cell line, was tested using a CytoTox 96 kit (Promega, Madison, WI, USA) according to the manufacturer’s instructions. Briefly, K562 cells and PBMCs (including NK cells) were resuspended at a 30 : 1 ratio (PBMCs : K562) in RPMI-1640 containing 5% FBS, and incubated in 96-well round-bottomed plates for 5 h at 37°C. During this incubation, NK cell-mediated lysis of target cells caused lactate dehydrogenase (LDH) to be released into the medium. Spontaneous release of LDH from PBMCs or target cells was measured by a separate incubation of the respective populations. Maximum LDH release was measured by adding detergent to lyse all of the target cells (positive control). At the end of incubation, any cells that remained intact were centrifuged, and 50
PBMCs (
The ITT (intent-to-treat) sample set was composed of volunteers who were tested for the main evaluation variable one or more times after the oral administration of
To evaluate the effect of
One-hundred-and-two healthy adults were recruited for this study between August 2010 and May 2011. Of the three subjects who did not pass the screening tests, the most frequent reasons for exclusion were that the individuals did not meet the selection criteria and/or were not assigned a random number due to an omission or administrative errors. The overall noncompletion rate was 15.7% (16 subjects); these subjects, who failed to meet the compliance requirements, violated the selection/exception criteria, became lost to follow-up, or withdrew agreement, were excluded from the PP analysis (Figure
Distribution of study volunteers.
The characteristics of the study participants in each treatment group are presented in Table
Demographic characteristics of the study subjects.
Category | Low dosage | High dosage | Placebo | Total |
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Sex | |||||
Male | 5 (15.2%) | 4 (12.1%) | 6 (18.2%) | 15 (15.2%) | |
Female | 28 (84.9%) | 29 (87.9%) | 27 (81.8%) | 84 (84.9%) | 0.7900 |
Age | |||||
Mean ± SD |
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Median | 51.0 | 53.0 | 54.0 | 53.0 | |
Min~max | 20.0~57.0 | 20.0~64.0 | 20.0~68.0 | 20.0~68.0 | 0.2281 |
To evaluate the primary efficacy of
Lytic activity of PBMCs in the intention-to-treat (ITT) group. PBMCs were isolated from the test subjects who were treated with the low dosage of
Lytic activity of PBMCs in the per-protocol (PP) group. PBMCs were isolated from the test subjects who were treated with the low dosage of
We hypothesized that the increased cytotoxic effects of PBMCs from donors that received high doses of
PBMCs from healthy donors were incubated with or without
PBMCs from healthy donors were incubated with or without
NK cells, which are essential elements of the immune defense against pathogens and tumor cells, can modulate both innate and adaptive immune responses and are directly cytotoxic against virus-infected and tumor-derived cells. Many strategies have been investigated to enhance NK cell activity. Among them,
The treated and untreated donors did not show any significant difference in abnormal diagnoses or clinically relevant changes in laboratory parameters, vital signs, or other safety parameters.
In conclusion, this randomized double-blind placebo-controlled trial revealed that a high-dosage of
The authors declare that they have no conflict of interests.
Kyung-Soo Kim and Tae-Young Lee equally contributed to this work.
This work was supported by Grants of National R&D Program for Cancer Control (0720510), Ministry of Health and Welfare, Republic of Korea, and a Grant from KRIBB Initiative Program to H. Poo.