Medical Ozone And Immune System
OZONE AS A MODULATOR OF THE IMMUNE SYSTEM
Alessandra Larini, Carlo Aldinucci and Velio Bocci
Institute of General Physiology, University of Siena, 53100, Siena, Italy
In order to clarify the immunomodulating properties of ozone, we have investigated: a) the effects of stimulation on isolated peripheral human blood mononuclear cells (PBMC) from normal donors with either ozone or ozonated serum; b) the range (in terms of O3 concentrations) of the therapeutic window; c) the stimulatory and toxic effects and d) the pattern, of both proinflammatory and immunosuppressive cytokine production up to 86 hours after exposure to O3. Results show that ozone can act as a weak inducer of cytokines producing IL-6, IL-4, TNF-α, IFN-γ, IL-2 and IL-10 and, most importantly, there is a significant relationship between cytokine production and ozone concentration. Analysis of the proliferation index shows that progressively increasing O3 concentrations inhibit IP and therefore appear cytotoxic.
Leukocytes comprise a heterogeneous cell population composed of lymphocytes (20-25%), monocytes (about 5%) and three type of granulocytes of which the neutrophils are about 70%. We have been the first to show that an appropriate ozone dose can induce a small release of interferon γ (IFN- γ) from human blood (Bocci and Paulesu, 1990). Later on the number of cytokines has expanded to IFN-β, interleukin 2 (IL-2), IL-6, IL-8, tumor necrosis factor α (TNF-α), transforming grow factor β1 (TGF-β1) and granulocyte-monocyte colony stimulating factor (GM-CSF) (Paulesu et al., 1991; Bocci et al., 1993a, b; 1994; 1998a, b). Later on several authors (Beck et al., 1994; Arsalane et al., 1995; Jaspers et al., 1997) have confirmed that ozone can induce the production of cytokines after that epithelial cells of the respiratory mucosa have been in contact with ozone.
Our results were obtained by ozoning blood directly and cytokines were detected in the plasma during the following 4-8 hours of incubations. These initial studies shed light on several aspects such as the protective effect of blood antioxidants, the dissimilar production of different cytokines and the progressive inhibitory activity of increasing ozone concentrations, particularly above 80 µg/ml per ml of blood. However they had limitations because firstly, whole blood can be incubated only for a limited time and, most importantly, we could not decide which cell type produced the cytokines.
During the last year we decided to isolate from normal blood donors either peripheral blood mononuclear cells (lymphocytes and monocytes, PBMC) in order to investigate their viability and the production and type of cytokines released after two different ozonation modalities. The first is a direct ozonation of PBMC suspended in human serum, so that cells undergo the total action of ozone due to immediate effects by hydrogen peroxide (H2O2) and other unidentified reactive oxygen species (early ROS), with very short half-life, and late effects, provided by lipid oxidative products (LOPs), with fairly long half-life. The second approach has examined the effect of ozonated serum 20 min before addition to PBMC and therefore ozone activity is expressed only by “late LOPs”.