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.