Seroimmunological characteristics of Korean workers exposed to toluene diisocyanate

Since type I allergy caused by specific IgE antibodies may play principal roles and IgG antibody-mediated reactions have been thought to be involved in some parts of the pathogenesis, this study was performed to investigate the role of IgE- or IgG-mediated hypersensitivity reactions in development of toluene diisocyanate (TDI) asthma in Korean workers. For 81 TDI spray painters, self-administrative questionnaires and direct interviews on respiratory symptoms, chest auscultation, and measurements of forced vital capacity (FVC) and forced expiratory volume in 1 sec (FEV1.0) were performed. The TDI concentration in their working environments was measured. Levels of serum IgE and IgG specific to TDI were estimated by radioallergosorbent test (RAST) and ELISA using p-tolyl isocyanate-human serum albumin (TMI-HSA) as the antigen. When sputum, cough, and dyspnea aggravated by work or wheezing existed, when FVC or FEV1.0 was less than 80% of the normal reference value, or when IgE RAST for TDI was positive, the peak expiratory flow rate (PEFR) was recorded four times per day for over 2 weeks. If decrease of PEFR was over 20% of baseline PEFR and changing pattern of PEFR was closely related to workshift in time, then a diagnosis of TDI asthma was made. Changing patterns of PEFR of 8 (9.9%) workers corresponded to the diagnostic criteria of TDI-related occupational asthma. Levels of the specific IgE were increased in 9 (11.1%) of the 81 subject workers and in 3 (37.5%) of the 8 PEFR-positive workers. Levels of the specific IgG were increased in 9 (11.1%) workers, and in only 1 (12.5%) of the asthmatics sensitive to TDI. Neither elevated TDI-specific IgE levels nor PEFR test positivities were associated with increased IgG levels. The mean titer of the PEFR-test-positive workers was slightly lower than that of the PEFR-negative workers and that of the IgE RAST-positive workers lower than that of the test-negative workers, but there was no statistical significance. These results suggest that IgG is not deeply involved in the pathogenesis of TDI-induced occupational asthma in Korean workers.