5 Respiratory Allergy to Synthetic Resins

Abstract

Human hypersensitivity responses to acid anhydride compounds have been recognized with increased frequency. The most extensive use of acid anhydride compounds is in the production of synthetic resins. Clinical sensitization to phthalic anhydride (PA), hexahydrophthalic anhydride (HHPA), tetrachlorophthalic anhydride (TCPA) and himic anhydride (HA) usually presents as an asthma/rhinitis syndrome. Workers sensitized to trimellitic anhydride (TMA) may also develop IgE-mediated asthma/rhinitis, but in addition they may exhibit late respiratory symptoms (LRSS) and a unique syndrome characterized by pulmonary infiltrates and anaemia (PDA). Non-immunological irritant effects may also occur after overexposure to any of these compounds. Clinical diagnosis is established by a careful occupational history, skin tests, serial pulmonary function tests and confirmed by bronchial challenge conducted under controlled laboratory conditions. Phthalic anhydride IgE-mediated reaction skin tests can be performed with either unconjugated PA or PA carrier protein reagents. Skin tests with TCPA- or TMA-protein conjugates have been used successfully for in vivo diagnosis of workers developing the asthma/rhinitis syndrome after sensitization to these substances. Several in vitro immunological tests are also useful for diagnosis and serial surveillance studies in the workplace. Total IgE, specific IgE, total antibody binding and specific IgG antibody responses can be measured accurately for these purposes. Total IgE and specific IgE reactions are associated with IgE-mediated asthma while total antibody and specific IgG levels are more apt to be higher in patients with LRSS. Specific IgG antibodies may be protective in some workers who develop high levels of specific IgE without having clinical sensitivity. Antibody responses to these materials probably involve specificities directed toward haptens and new antigenic determinants within the carrier proteins. Patients who develop severe respiratory symptoms to any of these acid anhydride compounds should be removed from further contact or exposure with these materials.