Enhancement of NK Cell Cytotoxicity Induced by Long-Term Living in Negatively Charged-Particle Dominant Indoor Air-Conditions

<div><p>Investigation of house conditions that promote health revealed that negatively charged-particle dominant indoor air-conditions (NCPDIAC) induced immune stimulation. Negatively charged air-conditions were established using a fine charcoal powder on walls and ceilings and utilizing forced negatively charged particles (approximate diameter: 20 nm) dominant in indoor air-conditions created by applying an electric voltage (72 V) between the backside of the walls and the ground. We reported previously that these conditions induced a slight and significant increase of interleukin-2 during a 2.5-h stay and an increase of NK cell cytotoxicity when examining human subjects after a two-week night stay under these conditions. In the present study, seven healthy volunteers had a device installed to create NCPDIAC in the living or sleeping rooms of their own homes. Every three months the volunteers then turned the NCPDIAC device on or off. A total of 16 ON and 13 OFF trials were conducted and their biological effects were analyzed. NK activity increased during ON trials and decreased during OFF trials, although no other adverse effects were found. In addition, there were slight increases of epidermal growth factor (EGF) during ON trials. Furthermore, a comparison of the cytokine status between ON and OFF trials showed that basic immune status was stimulated slightly during ON trials under NCPIADC. Our overall findings indicate that the NCPDIAC device caused activation of NK activity and stimulated immune status, particularly only on NK activity, and therefore could be set in the home or office buildings.</p></div

Changes of NK activities in individual healthy Volunteers.

<p>Each volunteer experienced ON and OFF trials of SUMICAS setting as indicated. The active (%) NK activities in individual volunteers were plotted when the NK activities were measured as NK and Target cells in 10:1 (the left panels) and 20:1 (the right panels). The “ON” showed the data obtaining after living in three months ON period and “OFF” indicated the data measuring after living in three months “OFF” period.</p

The SUMICAS setting for NCPDIAC was done by Artech Kohboh Ltd. and Yamada SXL Home Co. Ltd.

<p>The appearance of the SUMICAS device is shown panel A, and has an approximate size of 30(H) x 20 (W) x 4(D) cm. Volunteers switched the device ON or OFF by themselves every three months when blood and urine samples were obtained for biological monitoring (B). After pre-sampling for blood and urine, all volunteers turned SUMICAS ON and then switched SUMICAS either OFF or ON every three months. A total of 16 OFF to ON trials (On trial) have been safely conducted so far, as well as 13 OFF to ON trials (Off trial). The longest two volunteers completed 4 ON trials and 3 OFF trials over a period of one year and nine months. The shortest volunteer completed only 2 ON trials and 1 OFF trial because he was subsequently transferred to another location by his employer. The positively and negatively charged particles in the representative six rooms at where SUMICAS apparatus was set were measured using as Ion Counter (EM-1000, Eco Holistic Inc., Suita, Japan) during OFF period (indicated as control, panel C) and ON period (indicated as Sumicas, panel D).</p

A multi-regression test (left panel) and stepwise multi-regression test (right panel) were performed using the changed actual concentrations of cytokines after ON or OFF trials relative to those before trials.

<p>These tests extracted cytokines that changed during ON or OFF trials and their values were applied as the variable items to detect ON or OFF trials when changes of cytokines showed a certain number. The number 1.0 was applied for ON trials and 0.0 was applied for OFF trials in both regression tests. Multi-regression analysis extracted the changed actual concentrations of EGF, GM-CSF and IP-10 as the significant variables with statistical significance. The formula to detect an ON trial is “0.6082 - [GM-CSF] x 0.05426 + [EGF] x 0.00563]–[IP-10] x 0.00571”. The stepwise analysis only extracted EGF from the eight cytokines tested. The formula is “0.5434 + [EGF] x 0.00895”. Significant differences were found with both formulas when used to detect whether NCPDIAC was ON or OFF during a three-month trial period using individual changes of after-minus-before trial values of the actual cytokine concentration from each volunteer.</p

Changes of Log₁₀ concentrations of EGF, Eotaxin, G-CSF and IP-10 in plasma during ON and OFF trials of NCPDIAC and comparison of the elevation/reduction of both cytokines between ON and OFF trials.

<p>The Log₁₀ concentrations of EGF, Eotaxin and G-CSF tended to be increasing during ON trials, and comparison of changes (elevation or reduction) between ON and OFF trails showed a tendency of higher in ON trials. The IP-10 showed the tendency of reduction during OFF trials.</p

Changes of the actual concentrations of EGF in plasma during ON and OFF trials of NCPDIAC and comparison of the elevation/reduction of both cytokines between ON and OFF trials.

<p>The plasma concentration of EGF increased significantly during ON trials. In addition, comparison of the changes (elevation and reduction) of concentration of EGF between On and OFF trials showed a tendency of elevation in ON trials.</p

Schematic summary of previous experiments and development of negatively charged-particle dominant indoor air-conditions (NCPDIAC).

<p>(A) NCPIADC was established by painting a charcoal coating made by fine charcoal powder onto the wall and ceiling of a room. The charcoal coating designated as Health Coat was produced by Artech Kohboh Co. Ltd. In addition, a forced negatively charged-particle dominant indoor air condition was created by applying an electric voltage (72 volts) between the backside of the walls of a room and the ground. (B) The 2.5-hour stay experiments were performed using small rooms with or without NCPDIAC conditions. Sixty healthy volunteers were admitted to the rooms and biological monitoring was initiated regarding common blood testing, measures for the autonomic nerve system, and immunological parameters such as cytokines. Results revealed a small but significant elevation of interleukin (IL)-2 after entering NCPDIAC rooms. (C) Night-stay experiments over a period of 2 weeks were conducted with volunteers staying in a dormitory fitted with the NCPDIAC devices, and various biological parameters were monitored including those involved in the short-term experiments, as well as NK cell activity, since these parameters may be altered after two weeks. Results showed that NK cell activity was the only parameter exhibiting a significant change. Schematic biological changes caused by NCPDIAC is also presented in the right side of figure. NCPDIAC caused a slight but certain increase of IL-2 during short-term and mid- to long-term (weeks to months) exposure periods and induced NK cell killing activities due to the recurrent and accumulated elevation of IL-2.</p