RAGWEED-SPECIFIC ANTIBODIES IN BRONCHOALVEOLAR LAVAGE FLUIDS AND SERUM BEFORE AND AFTER SEGMENTAL LUNG CHALLENGE - IGE AND IGA ASSOCIATED WITH EOSINOPHIL DEGRANULATION

Background: Migration of eosinophils and release of eosinophil degranu lation products into bronchoalveolar lavage fluid is a consistent find ing in studies of late responses to allergen challenge in the lung. Ho wever, the mechanism of eosinophil activation and release of eosinophi l products in vivo is unclear. Objective: We investigated the hypothes is that antigen-specific IgG, IgA, secretory IgA, or IgE is responsibl e for the eosinophil activation observed in the late-phase pulmonary r eaction. Methods: Ragweed-specific IgE, IgA, secretory IgA, and IgG we re measured by monoclonal antibody-based immunoassays in bronchoalveol ar lavage (BAL) fluid and in serum from 19 asthmatic subjects allergic to ragweed and six healthy nonallergic control subjects before and 20 hours after segmental lung challenge with ragweed extract. Eosinophil cationic protein (ECP) was also measured in BAL fluid as a marker of eosinophil activation. Results: Most allergic asthmatic subjects had d etectable levels of ragweed-specific IgE, IgA, and IgG in their serum and BAL fluid, whereas normal subjects had ragweed-specific IgA with n o ragweed-specific IgE and little ragweed-specific IgG. IgA was the do minant ragweed-specific antibody isotype in BAL fluids. Ragweed-specif ic sIgA (r(s) = 0.52, p = 0.02) and IgA (r(s) = 0.50, p = 0.03) in BAL fluid after segmental lung challenge were significantly correlated wi th ECP. Ragweed-specific IgE and IgA in serum also correlated with ECP (r(s) = 0.74, p < 0.001 and r(s) = 0.48, p = 0.04, respectively). Con clusions: The correlation of allergen-specific IgA and IgE antibody le vels with ECP as a marker of eosinophil degranulation suggests an impo rtant role for IgE antibodies in allergic pulmonary inflammation and a potential role for antigen-specific IgA in eosinophil degranulation i n the lung after antigen challenge.