Int Arch Occup Environ Health ( 1989) 61:483-486 international Archivesof Occupationaln Environmental © Springer-Verlag 1989 Occurrence and specificity of Ig E antibodies to isocyanates in occupationally exposed workers S Cvitanovih l , Lj Zekan 2 , and M Marui 3 'Department for Pulmonary Diseases, Firule Clinical Center, Spinciceva 1, YU-58000 Split, Yugoslavia 2 Department of Nuclear Medicine, Firule Clinical Center, Split, Yugoslavia 3 Department of Physiology and Immunology Unit of the Department of Clinical Laboratory Diagnostics, Zagreb University School of Medicine and Zagreb Clinical Center, Zagreb, Yugoslavia Summary The levels of Ig E antibodies specific for toluene-diisocyanate (TDI), diphenylmethane-diiso- cyanate (MDI) and hexamethylene-diisocyanate (HDI) were determined in eight workers with an unequivocal history of professional asthma, all having been ex- posed to isocyanates in the working atmosphere Five workers were examined at the clinical onset of asthma. They had serum Ig E antibodies specific for TDI, MDI and HDI, and depressed pulmonary ventilation para- meters In contrast, three workers, who had only a mild bronchial obstruction at the time of testing, had no anti-isocyanate Ig E antibodies The results indi- cated that asthma was induced by type I allergic reac- tion, but other pathogenetic mechanisms of bron- choobstruction could not be completely ruled out. Key words: Respiratory sensitivity TDI MDI HDI Introduction Due to their excellent chemical and mechanical prop- erties, during the past 20 years polyurethanes have gained a considerable industrial importance Simul- taneously, however, the occupational health prob- lems related to their ever increasing manufacture have also become more important Bronchial hypersen- sitivity reactions ascribed to the occurrence of iso- cyanates in the working atmosphere constitute the major of these health problems l 10, 15, 20, 21 l How- ever, whereas the ability of isocyanates to cause bronchial hypersensitivity reactions is well known l 2, 10-18, 20-24 l, the pathogenesis of bronchoobstruc- tion has still remained unresolved Isocyanate-specific Ig E antibodies have often been difficult to detect in Offprint requests to: S Cvitanovic the sera of sensitized individuals, probably due to high chemical reactivity of diisocyanate l 14 l Our present study revealed that asthma in workers occupationally exposed to isocyanates was induced by type I allergic reaction However, since in three workers with mild bronchoobstruction specific Ig E antibodies were not detected, other pathogenetic mechanisms of bron- choobstruction could not be definitely excluded. Subjects and methods Study population Seven employees of a shoemaking factory and one worker in a polyurethane foam car seat factory (4 women: average age 34 years and 4 men: average age 38 years) were examined Six shoemakers had been intermittently ex- posed to isocyanates, during the production phase of gluing soles to the shoes, whereas one shoemaker and the car seat fac- tory worker had been exposed continuously All workers had work-related attacks of dyspnea and wheezing They were clini- cally examined and tested for hypersensitivity with skin tests using standard inhalation allergens Lung functional tests were conducted, and total Ig E and specific serum Ig E to toluene- diisocyanate (TDI), diphenylmethane-diisocyanate (MDI) and hexa-methylene-diisocyanate (HDI) determined. The control group consisted of 20 healthy individuals, 10 women (average age 35 years) and 10 men (average age 36 years), who had never been exposed to isocyanates They were tested according to the same protocol, and proved negative in skin tests for standard inhalation allergens, and RAST for TDI, MDI and HDI Their PRIST Ig E were within normal values. Allergens Standard inhalation allergens were used: house dust, mites Dermatophagoides pteronyssinus, mixed grass, Parietaria officinalis weed and tree pollens, epidermal and animal pro- teins, and moulds They all were products of the Institute of Immunology, Zagreb P officinalis pollen allergen was pre- pared as previously described l 7 l. Skin tests Intracutaneous skin testing was utilized Histamine hydrochloride ( O 1 mg/ml) was used as positive and 0 9 % NaCl with 0 5 % phenol as negative controls Testing protocol was or-