Allergy to insects in Japan. II. The reaginic sensitivity to silkworm moth in patients with bronchial asthma

The reaginic sensitivity to extract of silkworm moth wing (silkworm wing) and to that of silkworm moth body (silkworm body) was studied in 50 randomly selected asthmatic patients. Although none of the patients had occupational exposure to silkworm moth, 34 (68.0%) of these patients showed positive reaction to silkworm wing while 28 (56.0%) patients reacted positively to silkworm body following intracutaneous injection(s). Radioallergosorbent tests (RASTs) showed that 22 (44.0%) of 50 sera were positive to silkworm wing and 11 (22.0%) sera were positive to silkworm body, with less uptake of ¹²⁵I-labeled anti-immunoglobulin E in silkworm body than in silkworm wing RASTs. This suggests that wing components are more common sensitizers than body components. A fairly high percentage of these 50 patients also showed reaginic sensitivity to the extracts of butterfly, moth, and mite. That is, 26 (52%), 22 (44%), and 32 (64%) of these 50 patients had butterfly-, moth-, and mite-specific IgE antibodies in their sera, respectively. The seasonal variations of silkworm wing-, butterfly-, moth-, and mite-specific IgE antibodies and mutual RAST inhibition tests revealed that IgE antibodies to silkworm wing, butterfly, and moth were identical but all differed from the antibody to mite. These data suggest that the extract of silkworm wing is useful for the detection of allergy to moth and butterfly and also provides a suitable allergen source of unlimited quantity and consistent quality. It was also shown that the allergy to Lepidoptera (moths and butterflies) in Japan is found as commonly as that to mite, but without cross-reactivity between them.