Gastrointestinal specific immune response

The above scientific information on rice bran phytochemicals indicates that a multitude of mechanisms are operating at the cellular level to bring about specific health effects. Several health benefits of rice bran appear to be the result of the synergistic function of the many phytochemicals, antioxidants, vitamins and minerals which operates through a specific immune response. Their role in the biochemical mechanisms at the cellular level which result in major health effects is shown in Fig. 17.1. A short overview summarizing the effect of the various phytochemicals on major health issues such as cancer, immune function, cardiovascular disease, diabetes, altered liver function and gastrointestinal and colon disease will be given below. 

Barrier function is also supported by the gastrointestinal immune system much of the epithelium is bathed in immunoglobulin A (IgA), which is secreted from sub-epithelial plasma cells and transcytosed across the epithelium into the lumen. IgA provides an antigenic barrier by binding bacteria and other antigens, although this barrier function is specific for particular antigens and requires previous exposure for development of the response. 

The immune system is characterized by a unique distribution, and many of its components are located close to the principal sites of absorption, including the gastrointestinal tract, the pulmonary tract, and the skin. Therefore, the immune system is in a position to be exposed to potentially high concentrations of drugs and chemicals. This phenomenon is especially important in hypersensitivity responses where the primary portal of entry of the hapten can determine the specific site of the reaction. 

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