ACUTE RESPIRATORY DISORDER, RHINOCONJUNCTIVITIS AND FEVER ASSOCIATED WITH THE PYROLYSIS OF POLYURETHANE DERIVED FROM DIPHENYLMETHANE DIISOCYANATE

OBJECTIVES - A case is described of complex reactions associated with exposure to diphenylmethane diisocyanate (MDI), with some immunologic observations. METHODS - Medical history, clinical examinations, and an alyses of immunologic parameters and the 4,4'-MDI-related amine 4,4'-d iaminodiphenylmethane (MDA) in hydrolyzed serum and urine were used. R ESULTS - The patient, a mechanic whose medical history suggested repea ted attacks of a work-related pulmonary or systemic disease, was exami ned because of acute respiratory disorder, rhinoconjunctivitis, and a late systemic reaction after exposure to polyurethane pyrolysis produc ts, including 4,4'-MDI (air level 15 mug . m-3). Spirometry showed a p artly reversible obstructive dysfunction, and a skin-prick test was po sitive versus isocyanates conjugated with human serum albumin (HSA). M DA was detected in hydrolyzed serum (5.6 ng . ml) and urine (1.6 mug . g creatinine-1). In serum, there were specific immmunoglobulin (Ig) G (IgG1 and IgG4) and IgE antibodies to 4,4'-MDI-HSA and other isocyana tes (phenylisocyanate, toluene diisocyanate, p-toluene monoisocyanate, hexamethylene diisocyanate) conjugated with HSA, a very high total Ig E, a raised total IgG, and moderate neutrophilia and eosinophilia. The specific antibodies declined, but were still increased five years lat er. Furthermore, the values of circulating immune complexes were high. In vitro, the circulating immune complexes in serum increased after t he addition of 4,4'-MDI-HSA. The patient had anti-C1q antibodies, whic h probably accounted for part of the circulating immune complexes. CON CLUSIONS - The reactions associated with MDI exposure (in combination with exposure to pyrolysis products) had features compatible with imme diate hypersensitivity and with a complement-mediated immune-complex r eaction.