A cross-sectional survey of 46 employees exposed to trimellitic anhydride

Gene expression changes induced by type IV allergy-inducible chemicals in dendritic cells

In the present study, the changes of gene expression profile in dendritic cell (DC)-derived DC2.4 cells sensitized with two allergenic chemicals were analyzed by microarray analysis to develop a basis for an in vitro assessment system of type IV allergenic chemicals. Consequently, 26 genes were significantly up-regulated, and 53 were down-regulated in both groups. Interestingly, some of up-regulated genes were associated with the maturation process of DCs. A set of genes was further evaluated by real-time reverse transcription-polymerase chain reaction to identify the gene expression changes specifically induced by type IV allergy-inducible chemicals in DC2.4 cells, and 2 possible candidates, syndecan-1 (Sdc1) and smoothened (SMO) genes were identified. Thus, up-regulation of Sdc1 gene and down-regulation of SMO gene in DC2.4 cells may be diagnostic markers for the screening of type IV-allergenic chemicals.

Occupational asthma caused by high-molecular-weight substances

More than 250 agents that are encountered in the workplace have been shown to induce asthma in susceptible individuals. It is estimated that 2% to 15% of cases of asthma may be occupational. High-molecular-weight substances, such as plant and animal proteins, enzymes, and large carbohydrate molecules, can induce IgE-mediated occupational asthma. The incidence of disease varies among industries and is dependent on the physiochemical properties of the agent, the level and duration of exposure, industrial hygiene, engineering practices, and host factors. Risk factors, common high-molecular-weight workplace antigens, diagnosis, treatment, and prognosis are discussed.

A clinical and immunologic study to assess risk of TMA-induced lung disease as related to exposure

The objective of this study was to determine whether there are trimellitic anhydride (TMA) exposure levels that are very unlikely to cause immunologically mediated respiratory disease. A 3-year clinical and immunologic survey study of 286 employees was conducted at a facility that manufactures TMA. Each employee was assigned an exposure classification from 1 (highest) to 5 (lowest). Of the 28 individuals in exposure class 1, 8 (29%) developed disease; of the 57 class 2 employees, 2 (4%) developed disease; of the 79 class 3 employees, 4 (5%) developed disease. Of the 98 class 4 employees and the 24 class 5 employees, none developed disease. Inasmuch as individuals in class 4 and 5 (TMA exposure < 0.002 mg/m3) are at low risk of developing disease due to TMA, it appears that they do not warrant routine inclusion in surveillance studies.

Immunoglobulin E antibody against environmental allergens in subjects with trimellitic anhydride-induced asthma

The purpose of this study was to assess the relationship between atopy and the development of occupational asthma as a consequence of exposure to trimellitic anhydride (TMA). A case-control study was performed, which comprised 16 employees identified as having TMA-induced asthma and 44 similarly exposed controls. Specific immunoglobulin E measurements in response to cat, dust mite, ryegrass, and ragweed antigens were performed. Fifty-six percent of cases and 29% of controls were found to be atopic (P = 0.098). We demonstrated that there was a trend toward employees with TMA asthma being more atopic than those without TMA asthma. Atopy as an assessment of risk for the development of TMA asthma is unlikely to be useful, although further investigation may be warranted.

The association between serum levels of Th cytokines and rhinoconjunctivitis caused by methyltetrahydrophthalic anhydride

BACKGROUND

There are few epidemiologic studies on the association between serum levels of T helper (Th) cytokines and allergic symptoms caused by sensitizing agents.

METHODS

A population of 147 workers from two condenser plants using epoxy resin with methyltetrahydrophthalic anhydride (MTHPA) underwent a questionnaire survey and serologic investigations. Total and MTHPA-specific IgE levels were measured by the Pharmacia CAP System, and serum levels of interleukin (IL)-4, IL-13, and interferon-gamma (IFN-gamma) by enzyme immunoassay.

RESULTS

A significant association was found between work-related eye and nasal symptoms and a range of atopic characteristics, including the frequency of positive specific IgE, specific and total IgE levels, and IL-4 levels. A positive correlation was observed between levels of IL-4 and IL-13 (r=0.42). Furthermore, multiple logistic analysis revealed significant contributions of specific IgE and IL-13 to the work-related symptoms. A similar but nonsignificant association was also found for IL-4 (P=0.07). On the other hand, a multiple regression model with specific IgE levels as a dependent variable showed a significant association with total IgE, but not with IL-4, IL-13, and IFN-gamma.

CONCLUSIONS

These results suggest that work-related eye and nasal symptoms are closely related to specific IgE antibodies, and that allergic responses, mediated by IgE, to MTHPA may lead to a shift in the balance between Th1 and Th2 cells.

The significance of specific IgG4 antibodies to methyltetrahydrophthalic anhydride in occupationally exposed subjects

BACKGROUND

A definitive role for allergen-specific IgG4 as either an anaphylactic or a blocking antibody, or both, remains controversial.

OBJECTIVE

A population of 148 workers from two condenser plants (A and B) using epoxy resin with methyltetrahydrophthalic anhydride (MTHPA) was studied to evaluate the significance of MTHPA-specific IgG4 antibody.

METHODS

The workers were evaluated through questionnaire and serological investigations.

RESULTS

Ninety-seven (66%) of the currently exposed workers had positive MTHPA-specific IgE. IgE-sensitized workers in each plant had significantly more eye and nose complaints than unsensitized workers (P < 0.03). As the result of multiple logistic analysis, specific IgE antibodies was the most important predictor of work-related symptoms and its effect was greater than that of specific IgG4 (odds ratio 16.7 and 3.68, respectively). These indicate an IgE-mediated mechanism in most cases of work-related symptoms associated with MTHPA exposure. However, it cannot be denied that specific IgG4 is an anaphylactic antibody. Furthermore, IgE-sensitized workers in these plants displayed work-related symptoms despite the presence of specific IgG4. The frequency of positive specific IgG4 in continuously exposed workers was significantly (P < 0.02) higher in plant A than in plant B, reflecting the difference of the MTHPA levels between the two plants. In plant A, the frequency of positive specific IgG4 was significantly (P < 0.002) higher in continuously exposed workers than in intermittently exposed workers. Multiple regression analysis also confirmed that plant and exposure style contributed significantly (P < 0.01) to the determination of specific IgG4 levels.

CONCLUSION

These results suggest that work-related eye and nasal symptoms are likely to be IgE-mediated, and that specific IgG4 may reflect the intensity of MTHPA exposure and may not act as a blocking antibody.

Risk factors for sensitisation to methyltetrahydrophthalic anhydride

OBJECTIVES

To examine an association between specific IgE to methyltetrahydrophthalic anhydride (MTHPA) and exposure time, atopic history, smoking habits, and total IgE concentrations.

METHODS

A cross sectional survey was carried out on a population of 148 workers from two condenser plants using epoxy resin with MTHPA, an acid anhydride curing agent known to cause allergy.

RESULTS

Using a Pharmacia CAP system with a MTHPA human serum albumin conjugate, specific IgE antibody was detected in serum from 97 (66%) out of the 148 workers exposed to MTHPA. Stepwise multiple linear regression analysis showed a striking relation between log concentrations of specific and total IgE (P < 0.0001). Furthermore, when the workers were divided into two groups according to a cut-off point (100 IU/ml) between low and high total IgE, current smoking was significantly (P = 0.025) associated with specific IgE production only in the group with low total IgE (< 100 IU/ml).

CONCLUSIONS

Smoking is the most significant risk factor for raising specific IgE to MTHPA in the group with low total IgE concentrations.

Risk factors for immunologically mediated disease in workers with respiratory symptoms when exposed to hexahydrophthalic anhydride

Occupational immunologic lung diseases caused by exposures to substances such as hexahydrophthalic anhydride are significant health problems. It would be useful to identify risk factors, other than exposure, for occupational immunologic lung diseases such as occupational asthma. Our objective was to identify risk factors for development of immunologically mediated disease in workers with respiratory symptoms associated with exposure to hexahydrophthalic anhydride. A medical and immunologic survey study was conducted of 33 employees with respiratory symptoms associated with hexahydrophthalic anhydride exposure. Of the 33 employees with respiratory symptoms, 20 had no immunologically mediated disease. Seven had both immunoglobulin E-mediated and immunoglobulin G-mediated disease, 5 had immunoglobulin E-mediated disease only, and 1 had immunoglobulin G-mediated disease only. Although larger samples would have rendered atopy a statistically significant risk factor (assuming effect replication), the associated effect strength represents less than a 16% improvement versus chance, which is indicative of marginal clinical significance. However, as expected, elevated levels of specific antibodies were statistically and clinically significant risk factors. Development of one type of immunologically mediated disease was highly predictive of development of the other type. In hexahydrophthalic anhydride-exposed employees with respiratory symptoms, development of immunologically mediated respiratory disease is most closely associated with presence of specific immunoglobulin E or immunoglobulin G antibodies. Neither race, age, smoking status, atopy, nor exposure levels emerged as significant risk factors in this symptomatic study population.

Total serum IgE in trimellitic anhydride-induced asthma

The objective of this study was to determine whether total serum IgE levels are elevated in workers with trimellitic anhydride-induced asthma as compared with anhydride-exposed workers without an occupational immunologic syndrome. Sera from 12 highly exposed workers with trimellitic anhydride-induced asthma, and from 31 similarly exposed workers without occupational immunologic disease, were assayed for total immunoglobulin E (IgE) levels by Total IgE II FAST analysis. The mean total IgE levels were 176.74 ng/mL and 34.55 ng/mL respectively. The difference between the two groups was statistically significant, but considerable overlap of IgE levels between groups was seen. In conclusion, although mean total IgE levels are significantly different between TMA-exposed workers with or without occupational asthma, the significant amount of overlap and poor sensitivity of the test preclude the use of this assay in the individual evaluation of these workers.