Development and transfer of immediate cutaneous hypersensitivity in mice exposed to aerosolized antigen.

We previously showed that BALB/c mice sensitized to ovalbumin (OVA) by brief daily inhalations of antigen over 10 consecutive days exhibit elevated antigen-specific serum IgE antibody levels and increased airways responsiveness. For the first time, we now show that animals sensitized in this fashion to either OVA or ragweed (RGW) develop immediate hypersensitivity skin test reactions when challenged 2 d after completion of the sensitization protocol. Skin testing, performed by direct assessment of wheal formation after intradermal injection of allergen, was sensitive and specific, since animals exposed to RGW by inhalation only responded to RGW, and OVA-sensitized animals responded only to OVA. Positive reactions were associated with mast cell degranulation, whereas control injections were not. Since only sensitized IgE high responder BALB/c mice but neither nonsensitized BALB/c mice nor OVA-sensitized IgE low responder SJL/J mice exhibited wheal responses, induction of OVA-specific IgE appeared to be essential for the mediation of OVA-specific immediate hypersensitivity reactions of the skin in this model. Passive cutaneous anaphylaxis (PCA) testing confirmed the presence of antigen-specific IgE in the serum. Mice that developed IgG (predominantly IgG2b) anti-OVA antibodies did not respond to OVA injection, indicating that OVA-specific IgG was not involved in this system. Further support for the role of IgE in the immediate hypersensitivity response included the wheal response to intradermal injection of anti-IgE antibody that occurred in OVA- and RGW-sensitized mice at 10-fold lower concentrations than in nonsensitized BALB/c mice and not in sensitized SJL/J mice. After transfer of mononuclear cells from peribronchial lymph nodes of OVA- or RGW-sensitized BALB/c mice, naive, syngeneic recipients developed antigen-specific IgE and specific immediate hypersensitivity responses, indicating that the local lymphoid tissue at the site of sensitization can transfer responsiveness to these allergens. These results demonstrate for the first time the ability to elicit and study IgE-mediated immediate skin hypersensitivity responses in the mouse and illustrate the association of increased antigen-specific and total serum IgE levels, airways hyperresponsiveness, and antigen-specific immediate cutaneous reactivity after sensitization to allergen via the airways.