Balb/c mice fed 0 mg, 20 mg of beta-carotene (BC) or 50 mg of vitamin E (Vit E) per Kg of diet for 7 weeks were immunized intraperitoneally with beta-Lactoglobulin (beta-Lg). Specific IgG and IgE anti beta-Lg were determined in the mouse sera by an enzyme-linked immunosorbent assay (ELISA), and the jejunum was used for assessment of local anaphylactic responses ex vivo in Ussing chambers. Short-circuit current (Isc), a measure of active ion transport, and epithelial conductance (G), a measure of passive ion permeability, were measured for each tissue. Specimens were also processed for examination by histological analysis. Compared with sensitized mice (unsupplemented mice), those fed BC or Vit E had lower beta-Lg-specific IgG (p < 0.001 and p < 0.0001, respectively) and IgE levels (p < 0.02 and p < 0.01, respectively). A secretory response reflecting local intestinal anaphylaxis was evident in sensitized mice, as indicated by an increase in Isc (p < 0.009). Sensitized mice demonstrated also an enhanced epithelial permeability as measured by conductance (p < 0.03). BC supplementation resulted in a significant decrease in secretory response (p < 0.02) with no effect on the epithelial permeability. Interestingly, the secretory response and epithelial permeability were significantly reduced by supplementation with Vit E (p < 0.02 and p < 0.009, respectively). These findings provide evidence for the first time that both BC and Vit E regulate epithelial ion transport, but it should be noted that only Vit E-supplemented mice showed a decreased tissue conductance, indicating protection from beta-Lg-induced epithelial permeability increase. Analysis of histological sections revealed that BC or Vit E treatment clearly reduced the microscopic lesions caused by beta-Lg sensitization.
