Antigens of powdered pearl-oyster shell causing hypersensitivity pneumonitis

We describe the identification and characterization of antigens of the pearl-oyster shell which caused hypersensitivity pneumonitis in a 42-year-old worker. He was occupationally exposed to the dust of this shell in the manufacture of different ornaments. In addition to a typical history, the diagnosis was confirmed through a workplace-related exposure test and high titres of antigen-specific IgG antibodies. By means of the immunoblot technique, several relevant antigens could be detected in the shell of the pearl-oyster. Control sera also contained immunoglobulins that bound to some electrophoretically separated bands; these could represent antibodies that react with lectin-like components in the shell in a nonimmunologic manner.