Examination of oral sensitization with ovalbumin in Brown Norway rats and three strains of mice

We studied the conditions needed to sensitize animals to the oral feeding o f food allergens, without induction of tolerance, in order to investigate t he allergenicity of orally ingested food proteins. Brown Norway (BN) rats w ere sensitized by daily OVA (ovalbumin)-gavage or by drinking OVA containin g water ad libitum and the ASA (active systemic anaphylaxis) response, as t he immediate hypersensitivity response to antigen stimulation after oral se nsitization, was examined. The oral administration of OVA by gavage produce d a higher OVA-specific IgE response and an increase in serum histamine aft er antigen challenge, as compared to those produced by drinking water. Next , we examined the effect of murine age, the oral feeding technique and the oral feeding dose on sensitization using BALB/c, B10A and ASK mice. Twenty- week-old mice showed the strongest OVA-specific IgE and IgGl responses and ASA-associated serum histamine contents increased with gavage in the three different age groups of BALB/c mice. Administering 0.1 mg of OVA by gavage daily for 9 weeks appeared to induce a higher response than administering I mg of OVA, in terms of OVA-specific IgE and IgGl antibody responses and AS A responses. Among the three strains of mice, B10A mice exhibited the highe st response in terms of OVA-specific IgE and IgG I antibody and ASA respons es. These findings suggested BN rats and B10A mice were suitable models for oral sensitization with antigen protein and that oral sensitization in mic e requires low dose, intermittent antigen intakes. (C) 2001 Elsevier Scienc e B.V. All rights reserved.