Effect of repeated oral administration of tobacco snuff on natural killer-cell activity in the rat

The effect of smokeless tobacco extract on murine T cell cytokine production

Exposure of oral tissue to components of smokeless tobacco (ST) increases susceptibility to oral cancer and periodontal disease. Altered T cell cytokine expression patterns due to ST components could affect the course of these oral diseases. To determine if ST components bring about changes in cytokine expression, T cells in whole splenic mononuclear cell populations (SPM) and enriched T cells, costimulated with anti-CD28 were exposed to 1:10(2) to 1:10(4) dilutions of ST extract and stimulated with anti-CD3, IL-2, IL-4, IFN-gamma and IL-10 were measured using enzyme immunoassays and RT-PCR. IFN-gamma production by enriched T cells costimulated with anti-CD28, was decreased at all concentration of ST while IL-10 production were decreased at 72 h in cultures with 1:10(2). IL-2 production was significantly increased upon exposure of T cells to 1:10(2) ST extract. ST did not significantly impact IL-4 production. Overall the data indicate that expression of key cytokines, IFN-gamma and IL-10, are consistently decreased upon exposure to ST while IL-2 is increased. Thus, exposure of T cells to physiological concentrations of ST can alter the T cell cytokine expression pattern as to potentially influence oral cancer and periodontal disease.

Immunotoxic effects of smokeless tobacco on the accessory cell function of rat oral epithelium

Smokeless tobacco (ST) is known to adversely effect the oral mucosa, but knowledge about the influence on immune defence is limited. Few studies have investigated the effect of ST on the local immune response. In the present study, we have assessed the effect of a crude Swedish moist snuff (SS) extract, alkaloids, and nitrosamines on T-cell mitogenic response to Con A using epithelial cells, including Langerhans cells, of the rat oral mucosa as accessory cells. SS extract at a concentration of 4% reduced the T-cell proliferation by 50% (IC50 = 4%). Pretreatment of either oral epithelial cells or T-cells with SS extract also gave a significant inhibition of T-cell proliferation. This effect was not obtained following preincubation with SS components as alkaloids and different tobacco-specific nitrosamines (TSNA). None of the tested compounds were found to possess any mitogenic properties. This in vitro study showed that SS extract can evoke an immunosuppressive effect on mitogen-driven T-cell proliferation using cells from oral epithelium as accessory cells. This effect was more pronounced when SS extract was employed compared to when the single SS components were used alone.

The effect of nicotine on murine CD4 T cell responses

T cells were exposed to various concentrations of nicotine or smokeless tobacco extract (STE) during in vitro immune responses in order to examine effects upon expression of T cell costimulatory counter-receptors, CD28 and CTLA-4, and cytokine production. Splenic mononuclear cells (SPM) were exposed to 1:10(2) to 1:10(3) dilutions of STE or 1-100 micrograms/ml nicotine during 48 and 72 h of stimulation with anti-CD3. Expression of CD28 and CTLA-4 was evaluated with flow cytometry and production and expression of IL-2, IL-4, IL-10 and IFN-gamma were evaluated using ELISA and RT-PCR. The data here indicate that the percentage of CD4+ T cells expressing CD28 declined while percentage and intensity of CTLA-4 expression increased with exposure to a 1:10(2) dilution of STE during the T cell response. Exposure to nicotine decreased the percentage of CD4+ T cells expressing both CD28 and CTLA-4 and decreased the intensity of CD28 expression. Responding T cells exposed to nicotine produced significantly less Th1 cytokines, IL-2 and IFN-gamma, but significantly more Th2 cytokines, IL-4 and IL-10. Cytokine specific mRNA expression was only slightly affected by the exposure to nicotine. Thus, exposure of T cells to physiological concentrations of STE or nicotine can alter the T cell expression of CD28 and CTLA-4, and the CD4 T cell cytokine expression pattern.