Severe Immediate Reactions to Biologicals Caused by Silk Allergy

Three patients developed severe, immediate allergic reactions after the injection of an immunizing agent. Each of the three patients gave a positive direct or passive transfer reaction to silk extract. This proved that the patients were allergic to silk and that it was this antigen, present as a contaminant in the biological products, which produced the allergic reactions in these patients. It is apparent that sufficient amounts of silk antigen become incorporated into the biological product as a result of filtration through silk membranes to be antigenically significant when given to a highly allergic individual.