Ultrastructural demonstration of specific IgG and IgE antibodies binding to Aspergillus fumigatus from patients with aspergillosis.

Aspergillus-induced diseases usually demonstrate elevated circulating antibodies belonging to different isotypes. The antigens currently used to detect antibodies are crude culture filtrate and mycelial extracts of A. fumigatus (Af). Most Af-associated diseases result from the inhalation of the spores of the organisms present in the environment. However, it is not known whether specific circulating antibodies directed only against spore or mycelia of Af exist in the sera of patients with Af-induced diseases. With colloidal gold we have investigated thin sections of spores and hyphae of Af for their reactivity with Af-specific IgG and IgE antibodies. The results indicate that both spores and hyphae reacted identically with IgG and IgE antibodies from patients. None of the sera from normal control subjects reacted in this system, although low levels of antibodies were detected in the sera by ELISA. Sera from both patients with allergic bronchopulmonary aspergillosis or aspergilloma reacted with cell envelope antigens, whereas sera from patients with invasive aspergillosis also bound to cell sap. This method therefore demonstrates localization of antigens binding to different isotypes in the sera from different clinical forms of aspergillosis and may be useful in purifying specific antigens for immunodiagnosis.