Latex-induced dermal and pulmonary hypersensitivity in rabbits

Natural rubber latex (NRL) causes immediate, IgE-mast cell-mediated reactions in sensitized individuals, especially among health care workers and children with spina bifida. The immunopathogenesis of the reaction is obscure.

To study the immunologic mechanisms of NRL allergy, rabbits were sensitized with two nonammoniated and one ammoniated NRL antigens. Subcutaneous and intratracheal injections were used to immunize rabbits. Intradermal skin tests, IgG antibodies against NRL in serum and lung lavage fluid, and pulmonary histologic features were evaluated.

One of nine sensitized rabbits died of anaphylaxis immediately after the third intratracheal injection with nonammoniated NRL. All sensitized rabbits, but not the controls, showed an immediate wheal and flare reaction in intradermal skin testing with NRL antigens. A positive skin reaction was detected 6 and 48 hours after the intradermal injections in four of five sensitized rabbits. A significant increase in NRL-specific IgG antibodies was detected in serum and lung lavage fluid of immunized rabbits. Lung histologic evaluation of NRL-sensitized rabbits showed a granulomatous interstitial and bronchial inflammation with a predominance of eosinophils and histiocytes in both intratracheally and subcutaneously sensitized rabbits. Vasculitis, hypertrophia, and contraction of pulmonary arteries could be detected in sensitized animals.

The results of the first NRL rabbit model study indicate that eosinophils and IgE antibodies play a major role in the immunopathogenesis of NRL-induced allergy and anaphylaxis. A wide range of inflammatory responses detected in rabbits injected by subcutaneous route without intratracheal exposure suggests that NRL exposure may pose a risk for a subsequent systemic reaction.