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Bystander suppression of collagen-induced arthritis in mice fed ovalbumin

BioMed Central
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  • Research Article
  • Biology


Introduction It is now well established that intestinal exposure to antigen decreases T-cell-mediated inflammation and spe- cific B-cell responses to the antigen in question. This ability of the intestinal immune system has been demon- strated, for example, with respect to antigens such as food proteins [1] and bacteria [2]. The capacity of the gut-asso- ciated lymphoid tissue to suppress certain immune responses to intestinal antigen is known as oral tolerance [3]. Several mechanisms have been suggested to be involved in this process, for instance anergy, clonal dele- tion of antigen-specific cells, and induction of antigen- specific regulatory cells [3,4]. Regulatory cells induced by feeding exert their action through secretion of nonspecific suppressive cytokines and/or by direct interactions with other cells [5–8]. Consequently, when the regulatory cells are activated, they suppress immune responses in their vicinity irrespective of the eliciting antigen. It has previ- ously been demonstrated that rats fed ovalbumin (OVA) and subsequently immunized subcutaneously with a mixture of OVA and human serum albumin have signifi- cantly lower IgE antibody and lower delayed-type hyper- sensitivity reactions to human serum albumin than controls [1]. The results of that study provided evidence that rats orally tolerant to one antigen suppressed T- and B-cell responses to an unrelated antigen, provided that the two antigens were injected subcutaneously in a mixture during the inductive phase. Collagen-induced arthritis (CIA) is the most common model for rheumatoid arthritis. Autologous or heterologous collagen type II (CII) emulsified in Freund’s complete adju- vant induces arthritis, with edema of the synovial tissue, synovial-cell proliferation, inflammatory-cell infiltration, and BCII = bovine collagen type II; CII = collagen type II; CIA = collagen-induced arthritis; ELISA = enzyme-linked immunosorbent assay; IFN = interferon; IL = interleukin; OVA = ovalbumin; PBS = phosphate-buffered saline;

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