Oral Sensitization of W/Wv Mice with Ovalbumin and Possible Involvement of the Decrease in .GAMMA..DELTA.-T Cells

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Abstract
Mast-cell-deficient WBB6F1-W/Wv mice (W/Wv) and congenic wild-type (+/+) mice were sensitized by oral administration of 0.1 or 1.0 mg ovalbumin (OVA) in the form of gavage every day for 9 weeks, and active systemic anaphylaxis (ASA) was induced by intraperitoneal injection of OVA. Production of OVA-specific IgG1 in response to oral sensitization of the W/Wv mice was very high, and the production of IL-4, IL-5 and IL-10 by splenocytes re-stimulated with OVA in vitro was increased. These findings suggest that Th2-dominant helper T-cell activation had occurred. By contrast, production of OVA-specific IgG1 was low in +/+ mice, and no significant increase in production of Th2-type cytokines by the splenocytes of +/+ mice was observed. Population analysis in Peyer's patches by flow cytometry revealed that the proportion of the CD11c+ cell in the W/Wv mice was slightly increased after antigen stimulation. Analysis of the cell surface markers of intraepithelial lymphocytes (IELs) by flow cytometry showed that the proportion of TCRγδ-T cells was extremely lower in the W/Wv mice, especially in the antigen sensitized group. The proportion of TCRγδ-T cells in the splenocytes of W/Wv mice was also lower than in +/+ mice. Taken together, the above findings indicate that W/Wv mice seems to be a good model not only for studying the induction mechanism of food allergy but for examining the role of TCRγδ-T cells in food-induced hypersensitivity.