DECLINE IN SERUM ANTIBODIES TO METHYLTETRAHYDROPHTHALIC ANHYDRIDE AFTER CESSATION OF EXPOSURE - IMPLICATIONS FOR USE AS A BIOMARKER

The association between exposure intensity and serum levels of immunog lobulins E and G against low molecular weight compounds was evaluated. The decay of levels of specific IgE and IgG antibodies was studied af ter cessation of exposure in workers exposed to the inhalant allergen methyltetrahydrophthalic anhydride in a plant using epoxy resins. Sera have been collected in workers for 18-84 (mean value 54) months after cessation of exposure. Specific IgE and IgG was assessed by RAST and ELISA, respectively The mean of individual half-times for IgE (N = 10) and IgG (N = 8) was 0.9 (range 0.1-1.8) and 0.4 (range 0.2-0.6) years , respectively, after total avoidance of exposure. Corresponding decre ases of IgE and Ige were also observed after reduction, but not total elimination, of exposure. No correlation was seen between biologic hal f-times of specific IgE and total IgE, atopy, smoking habits or gender . The results indicate that the levels of specific antibodies in sensi tized individuals reflect long term exposure, and may persist for year s after the end of exposure.