Areca-nut extract modulates antigen-specific immunity and augments inflammation in ovalbumin-sensitized mice

Areca-nut chewing has been linked to oral cancer and many other diseases, in which immune deterioration and tissue inflammation are plausibly involved. Recent studies reported that areca-nut extract (ANE) affected the functionality of lymphocytes and neutrophils in vitro. In the present study, we investigated the immunomodulatory effect of ANE in vivo. Ovalbumin (OVA)-sensitized mice were daily administered with ANE (5-50mg/kg) for 10 doses by intraperitoneal injection from days 1 to 5 and from 8 to 12. The mice were systemically sensitized with OVA on day 3, and their footpads were challenged with OVA to induce delayed-type hypersensitivity (DTH) reactions on day 13. The serum level of OVA-specific IgM and IgG1 was significantly attenuated by 5 and 25mg/kg of ANE, whereas OVA-specific IgG2a was markedly enhanced by 50mg/kg of ANE. The production of interferon (IFN)-γ by splenocytes reexposed to OVA in culture was markedly augmented by ANE (25 and 50mg/kg). In addition, ANE (25 and 50mg/kg) demonstrated an enhancing effect on DTH reactions, including the tissue swelling, the infiltration of CD3 ⁺ and F4/80 ⁺ cells, and the expression of IFN-γ and tumor necrosis factor (TNF)-α in the footpads challenged with OVA. The phagocytic activity and TNF-α production by the splenic CD11b ⁺ cells were also enhanced in ANE-treated groups. Taken together, these results demonstrated that ANE modulated antigen-specific immune responses and promoted inflammatory reactions in vivo, which may contribute to immune deregulation associated with areca-related diseases.