Insect Cell Stimulation by LPS Requires the Activity of Cell-Released Proteases

摘要

The hemocyte line BTI-EA-1174-Afrom the lepidopteran insect Estigmene acraea responds to bacterial lipopolysaccharide (LPS) by an enhanced phagocytic reaction and a dose-depen- dent increase of lysozyme release [Wittwer et al., Dev Comp [mmunoI21:323 (1997)]. This paper provides evidence for a strong proteolytic activ- ity in cell culture supernatants occuring after addition of LPS (1 mg/ml). The proteolysis is caused by cell-released proteases and seems to be necessary for cell activation. Its inhibition by IX2-macroglobulin results in a dose-dependent reduction in cel- lular response strength. Phagocytic reactions, as well as lysozyme release, are lowered to about half in the presence of [).0001 mg/ml ?2-macroglobulin. A nearly complete abolishment [)f activation was achieved with final concentrations of 1.0 mg/ ml ?2-macroglobulin. The data presented allow us to conclude that the LPS-triggered proteolytic activity is an important part [)f the activation process; it occurs outside of the cells and de- livers immune response activating factors. Arch. Insect Biochem. Physiol. 39:91-97, 1998.