[A case of occupational asthma caused by arrowhead scale in mandarin orange-worker]

A 50-year-old woman with occupational asthma, whose attacks were provoked by inhalation of Arrowhead scale (Unapsis Yanonensis Kuwana) attached to the leaves of mandarin oranges is reported. She experienced asthmatic attacks while picking leaves and harvesting mandarin oranges. Because Arrowhead scale-dust stuck to the leaves was suspected to be the allergen, tests of allergy were performed using an extract of the allergen prepared by Unger's method in our laboratory. Asthmatic attack was provoked 90 minutes after inhalation of the extract of cocoon. Histamine was not released, but leukotriene D4 production was induced by the addition of the extract to whole blood. Basophils were activated by addition of anti-IgG anti-sera as well as the extract. These data indicate that LT released from target cells in response to the worm elements, as well as histamine, is important as a chemical mediator.