High incidence of precipitins in sera of heroin addicts.

We analyzed sera of 50 consecutively hospitalized heroin-abuse patients for precipitins against several antigens. Forty-seven addicts had precipitins against extracts from moldy hay, and 34 against extracts from bagasse. Thirty-six showed precipitin bands against extracts from one or more of the following: Aspergillus, Micropolyspora faeni, and Thermoactinomyces vulgaris. These findings were significantly different from those of a control population (P less than .0001 for all antigens tested). The recent culture identification of bacteria and fungi from street heroin suggests that the addicted population may be injecting antigenic material intravenously, with subsequent antibody formation.