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.


CONCLUSIONS
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.
Yokota
K
K
Matsushita Science Center of Industrial Hygiene, Osaka University School of Medicine, Suita, Japan.
Yamaguchi
K
K
Takeshita
T
T
Morimoto
K
K
D000328:Adult; D000395:Air Pollutants, Occupational / Q000276:immunology*; D000918:Antibody Specificity / Q000276:immunology*; D016085:Bronchoconstrictor Agents / Q000276:immunology*; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D008297:Male; D008875:Middle Aged; D010796:Phthalic Anhydrides / Q000276:immunology*
D000395:Air Pollutants, Occupational; D016085:Bronchoconstrictor Agents; D007074:Immunoglobulin G; D010796:Phthalic Anhydrides; C088343:methyltetrahydrophthalic anhydride