A 2-CENTER STUDY FOR THE EVALUATION AND VALIDATION OF AN ANIMAL-MODELFOR THE ASSESSMENT OF THE POTENTIAL OF SMALL MOLECULAR-WEIGHT CHEMICALS TO CAUSE RESPIRATORY ALLERGY

This study evaluated a single intradermal injection model in the guine a pig with subsequent inhalation challenge and serological analysis as a method to predict the potential of chemicals to induce respiratory allergy. Four known respiratory allergens (trimellitic anhydride, diph enyl methane diisocyanate, phthalic anhydride and toluene diisocyanate (TDI)) were screened by two industrial research laboratories using th is protocol. Dinitrochlorobenzene, a potent contact allergen, was incl uded as a negative control material. In both laboratories, the respira tory allergens, but not the contact allergen, induced high titre antig en-specific antibodies in treated animals. The inhalation challenge re sults were similar in both laboratories but were less conclusive in th at exposure to free TDI failed to induce pulmonary responses, probably because it fails to penetrate to the deep lung in sufficient concentr ation. Although the assay shows promise as a means of identifying chem ical respiratory sensitisers, its use as a routine screen for the pred iction of the ability of materials to induce respiratory allergy in ma n is probably questionable.