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 G $_{i}$ and transducin, was found to inhibit the lipopolysaccharide-induced responses of the WEHI-231 B lymphoma cell line and the P388D $_{1}$ macrophage cell line. These results, combined with the demonstration that lipopolysaccharide inhibits adenylate cyclase activity in P388D$_{1}$ cells, strongly argues that lipopolysaccharide activation of cells is mediated by a G$_{i}$-likereceptor-effector coupling protein.