Topical skin exposure to dry trimellitic anhydride (TMA) powder induces specific IgE.
Zhang-XD; Murray-DK; Siegel-PD
FASEB J 2000 Apr; 14(6)(Suppl S):A1241
TMA is known to produce occupational asthma that associated with its ability to acylate proteins and to induce production of TMA-specific IgE. Though the respiratory tract is considered to be a major exposure route leading to sensitization, the potential role of dermal exposure is not known. Animal studies have shown that topical application of TMA dissolved in organic solvents can lead to specific IgE production. The present study examined the ability of dry TMA to dose-dependently sensitize Brown Norway rats when applied to the skin. A patch of hair was carefully clipped with scissors on the rat's back. Dry TMA powder (1.25, 5 and 20mg) was applied once per week for 4 weeks and the area occluded with dermal adhesive tape overnight. Residual powder was collected and analyzed by proton nuclear magnetic resonance (NMR) for both TMA and Its hydrolysis product, trimellitic acid. Some TMA hydrolysis occurred, but TMA was still the predominant component of the powder after application. Blood was taken 2 weeks after the last TMA application and anti-TMA IgE measured by ELISA. All doses of TMA elicited production of anti-TMA IgE and the titers were dose dependent. Specific IgE to TMA was not found in either unexposed controls or trlmellitic acid exposed rats. This data suggest that dry, reactive chemicals can penetrate the epidermis (possibly suspended or solubilized in skin oils), react to proteins and induce production of specific IgE.
Antibody-response; Skin-exposure; Bronchial-asthma; Workers; Worker-health; Work-environment; Occupational-exposure; Sensitization; Inhalation-studies; Laboratory-animals; Animals; Animal-studies; Models; Histopathology; Immunological-tests; Skin-tests; Antigens
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