The relationship of total serum IgE and blocking antibody in trimellitic anhydride-induced occupational asthma

Abstract

Clinical and immunologic evaluations were performed on workers who manufacture trimellitic anhydride (TMA), a chemical used widely in the plastics industry. Serum samples of 29 workers exposed to TMA dust and fumes were assayed for total IgE, as well as specific IgE and total antibody binding to radiolabeled trimellityl human serum albumin (TM-HSA). Fifteen workers were determined to have significant specific IgE to TM-HSA (≥ I ng of 125I-TM-HSA bound per milliliter). Of these 15 individuals, seven workers had immediate asthma and rhinitis and positive cutaneous prick tests and eight were nonasthmatic and skin test negative. Mean peak total serum IgE was significantly higher in the prick test positive group (p < 0.02) and higher than in 12 exposed asymptomatic IgE antibody-negative workers (p < 0.001). Total serum IgE followed rises and falls in TM-HSA-specific IgE binding, correlating to the onset of allergic symptoms in all seven workers. Total antibody binding of 125I—TM-HSA, as determined by the ammonium sulfate precipitation technique, was higher in the skin test-negative group of eight (mean 12,062 ng per milliliter 125I—TM-HSA bound) than in the seven symptomatic skin test-positive workers (mean 2930, p < 0.004). Determinations of total antibody divided by specific IgE (both in nanograms of 125I-TM-HSA bound per milliliter) or blocking ratios clearly discriminated the seven skin test-positive workers with TMA-induced asthma (range 10 to 666) from the eight skin test-negative workers (range 1580 to 16,000). Thus total serum IgE, blocking ratios, and specific IgE to TM-HSA were found to be useful indices for serologic diagnosis of TMA-induced immediate asthma and rhinitis.