ortho-Phthalaldehyde enhances allergen-specific IgE production without allergen-specific IgG in ovalbumin-sensitized mice

ortho-Phthalaldehyde (OPA) is commonly used as a safer and more effective chemical disinfectant for use with medical devices in hospitals. However, the cases of patients with occupational bronchial asthma or contact dermatitis are recently reported among workers in the medical professions who were exposed to OPA disinfectant. Mechanism of allergic reaction associated with OPA is poorly understood. The purpose of this study is that OPA may act as an immunological adjuvant in the allergic reaction accompanied by enhanced specific-IgE production in response to allergen challenge in OVA-sensitized mice. OPA induced increase of total cell numbers, and reflected infiltration of neutrophils in BAL fluid after allergen challenge in sensitized mice, dose-dependently. However, total protein concentration in BAL fluid did not change in the all of groups. The OPA induced up-regulation of eotaxin and monocyte chemotactic protein-1 mRNAs in the lung as well as the increase in OVA-specific IgE in sensitized mice compared with non-sensitized controlled mice without increase in the level of OVA-specific IgG. Cytokines IL-4 and IL-5 mRNA were expressed by allergen (OVA) challenge in both lungs collected from OPA-administrated-sensitized and OPA-administrated-nonsensitized mice. From these data, we concluded that low concentration of OPA that enhanced the OVA-induced recruitment of neutrophils to the lung and the production of allergen-specific IgE, suggesting that OPA acts as an immunological adjuvant.