The relationship of atopy, smoking, and sensitization to methyltetrahydrophthalic anhydride

We investigated the association of smoking, atopy and helper T (Th) cytokines with sensitization to methyltetrahydrophthalic anhydride (MTHPA) in occupationally exposed subjects. A population of 147 workers from two condenser plants using epoxy resin with MTHPA underwent a questionnaire survey and serologic investigation. 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-g) by enzyme immunoassay. The Pharmacia CAP-Phadiatop test, which detects serum IgE specific to most common aeroallergens, was also used. Ninety-six (65%) of the currently exposed workers had positive MTHPA-specific IgE. A significant difference was found in the frequency of positive specific IgE between atopic and non-atopic subjects (P<0.01), but not between smokers and non-smokers. As for smoking, the frequency of positive specific IgE was significantly (P<0.005) higher in smokers than that in non-smokers in non-atopic subjects. Multiple logistic regression analysis also confirmed significant contribution of atopy and smoking to the development of specific IgE (odds ration=3.2 and 10.5, respectively), suggesting that atopic subjects who became sensitized to P<0.01 may become sensitized to common aeroallergens. On the other hand, none of the Th cytokines contributed to the elevation of specific IgE levels. These results suggest that atopic subjects and non-atopic smokers are at increased rist of sensitization by P<0.01. However, to evaluate conclusively the effect of atopy on sensitization, further prospective studies are necessary.