Nightly asthma caused by allergens in silk-filled bed quilts: clinical and immunologic studies

Bed quilts filled with silk waste were found to cause nightly attacks of asthma. The first symptoms appeared on an average after 7 mo of exposure at a mean patient age of 30 yr. About 50% of the patients could be classified as atopic. Extract of the filling material revealed positive scratch and RAST tests in most patients. The bed quilts were advertised as being filled with pure wild silk (from silk moths of the genus Antheraea feeding on oak leaves), but it was found that in most cases the filling also included waste of cultivated silk (Bombyx mori). The origin of the allergen was sought. Since textile products of silk are considered to be practically nonallergenic, some type of contaminant appeared the most likely candidate. No allergen was found in cocoons, chrysalis (pupa), or moths of Antheraea. However, some cocoons of Bombyx mori, usually in small amounts, and excretions of the silkworm did contain allergen. High concentrations of allergen were found in an extract of living insects of the genus Anthrenus that was present in one batch of Bombyx mori cocoons. Thus, the silk waste appeared to be contaminated with material from the silkworms and also with infesting insects, which together create a very potent allergen repertoire that after a short incubation time, in a considerable frequency, elicits a rise in asthmatic symptoms and high serum IgE antibody levels.