In vitro demonstration of specific IgE in phthalic anhydride hypersensitivity.

Clinical sensitization to phthalic anhydride occurred in a worker who developed symptoms of rhinorrhea, lacrimination, and wheezing after exposure to this chemical. Positive skin tests, provocative bronchial challenges, and a high serum titer of specific IgE (by the radioallergosorbent test) to phthalic anhydride corroborated his clinical hypersensitivity. Bronchial provocation studies using alcoholic-saline solutions of phthalic anhydride and phthalic anhydride dust resulted in immediate airway obstruction. The successful identification of specific IgE by the radioallergosorbent test demonstrates that this can be a useful in vitro technique for corroborating sensitization to this chemical.