IN-VITRO PHAGOCYTOSIS OF ESCHERICHIA-COLI AND RELEASE OF LIPOPOLYSACCHARIDE BY ADHERING HEMOCYTES OF THE SILKWORM, BOMBYX-MORI

A primary culture containing adhering hemocytes mainly granular cells from the silkworm, Bombyx mori, was used to investigate in vitro phago cytosis of Escherichia coil. Phagocytosis was confirmed to occur in th is system by microscopic observation. Lipopolysaccharide (LPS) concent ration in the culture medium was measured by a Limulus test and a high er LPS concentration was detected in phagocytosis-occurred samples tha n in control samples, which omitted either E. coil cells or adhering h emocytes. Moreover, it was found that LPS containing sample but not co ntrol samples strongly induces gene expression of cecropin B, an antib acterial protein. These results suggest that bacterial cell wall compo nents like LPS released by phagocytosis play an important role in the induction of insect antibacterial proteins. (C) 1997 Academic Press.