Immunostimulative effects of repeated inhalation exposure to microvesicle-bound endotoxin of Pantoea agglomerans

Rabbits exposed repeatedly to aerosols of endotoxin-containing microvesicles (ECMV) of the outer membrane of the Pantoea agglomerans strain isolated from airborne grain dust showed a large increase in the concentration of circulating cytokines: total interferon (IFN), interleukin-1 alpha (IL-1 alpha), and tumor necrosis factor alpha (TNF alpha). The increase was significantly higher compared to animals exposed to control saline (p<0.001). Aerosol exposure to ECMV also induced the formation of specific precipitin antibodies and lymphocyte activation. The results indicate strong immunomodulative properties of ECMVs produced in nature by Pantoea agglomerans bacteria, and heavily contaminating organic dusts.