Serum IgA antibodies to Aspergillus fumigatus in various stages of allergic bronchopulmonary aspergillosis.

With double antibody ELISA, serum IgA antibodies against Aspergillus fumigatus (Af) were measured from patients in stages I through V allergic bronchopulmonary aspergillosis (ABPA). All sera from patients with ABPA demonstrated considerably greater values for IgA-Af than sera from nonatopic subjects. When this sera was compared with sera from patients with asthma and immediate cutaneous reactivity to Aspergillus, the present studies documented markedly elevated serum IgA-Af in the acute, exacerbation, and fibrotic stages of ABPA. Some patients in remission or corticosteroid-dependent asthma stages also demonstrated increased values. Because the major stimulus to antibody production occurs in the lung in response to presence of Af hyphae, polymeric IgA antibodies could potentially contribute to immunologic lung damage in ABPA. Finally, large dose alternate day or daily prednisone that was administered to patients in the fibrotic stage of ABPA did not prevent the marked production of isotypic antibodies to Af.