Pertussis toxin inhibition of B cell and macrophage responses to bacterial lipopolysaccharide.

Lipopolysaccharide, a component of the outer membrane of Gram-negative bacteria, activates B lymphocytes and macrophages. Pertussis toxin, which inactivates several members of the G protein family of signaling components, including Gi and transducin, was found to inhibit the lipopolysaccharide-induced responses of the WEHI-231 B lymphoma cell line and the P388D1 macrophage cell line. These results, combined with the demonstration that lipopolysaccharide inhibits adenylate cyclase activity in P388D1 cells, strongly argues that lipopolysaccharide activation of cells is mediated by a Gi-like receptor-effector coupling protein.