Oral carrageenan induces antigen-dependent oral tolerance: Prevention of anaphylaxis and induction of lymphocyte anergy in a murine model of food allergy

Immunosuppressive effects of carrageenan, a high-molecular-weight polysacch aride, on antibody and T cell responses have been previously demonstrated. However, its effect on anaphylaxis is unknown. Our objectives were to test carrageenan-mediated oral tolerance induction in young mice subsequently se nsitized to a common cow's milk: antigen. C3H/HeJ mice were fed or not lamb da -carrageenan (0.5 g/L) and/or 0.01 mg/mL beta -lactoglobulin (BLG) for 5 d before oral sensitization with BLG and cholera toxin. Subsequently. the mice were challenged with BLG and symptom scores of anaphylaxis were record ed. Mesenteric lymph node cells, spleen cells, Peyer's patches cells, intra epithelial lymphocytes, and lamina propria lymphocytes were isolated and st imulated in vitro with BLG, IL-2, or left unstimulated. BLG-specific IgG, I gG(1), and IgG(2a) antibodies: were measured. Pretreatment with carrageenan and BLG, but not pretreatment with either carrageenan or BLG alone or omis sion of pretreatment, diminished significantly the number of anaphylactic m ice after BLG challenge (6.3% versus 53% in mice without pretreatment, p = 0.006). Mesenteric lymph nodes and spleen cells from pretreated mice prolif erated less in presence of BLG or IL-2 than cells from sensitized control m ice. Antigen-specific antibody production and passive cutaneous anaphylaxis was not suppressed by carrageenan and BLG pretreatment. In conclusion. car rageenan administered to young mice in conjunction with low doses of allerg en before sensitization efficiently prevents anaphylaxis.