MACROPHAGES EXPRESSING A FUSION PROTEIN-DERIVED FROM BACTERICIDAL PERMEABILITY-INCREASING PROTEIN AND IGG ARE RESISTANT TO ENDOTOXIN/

Objectives: To generate a recombinant fusion protein (FP) based on the endotoxin-binding domain of bactericidal/permeability-increasing prot ein (BPI) and the constant domain of IgG and to test its ability to in hibit lipopolysaccharide (LFS)-induced macrophage tumor necrosis facto r alpha (TNF-alpha) secretion. Design: A murine macrophage cell line, RAW 264.7, was transfected with a BFI-IgG FP before incubation with LP S. The amount of IFS-induced TNF-alpha protein secreted was measured a nd compared with that secreted by cells transfected with a control con struct. Setting: Basic science research laboratory. Main Outcome Measu re: Secreted TNF-alpha protein concentration. Results: After transfect ion, RAW 264.7-cell FP expression was detected in cell lysates and sup ernatants. At each LFS dose tested, cells transfected with the FP gene secreted less TNF-alpha than did cells transfected with a control con struct. Conclusions: The FF possesses substantial antiendotoxin activi ty, as delineated by inhibition of LFS-induced TNF-alpha secretion by murine macrophages transfected with the fusion gene construct. In the future, such FF may be used as a clinical reagent to reduce the morbid ity and mortality associated with serious gram-negative bacterial infe ctions in surgical patients.