Macrophages expressing a fusion protein derived from bactericidal/permeability-increasing protein and IgG are resistant to endotoxin
P. S. Dahlberg, R. D. Acton, M. E. Uknis, H. G. Klaerner, J. W. Johnston, C. D. Levelle, B. H. Gray and D. L. Dunn
Department of Surgery, University of Minnesota, Minneapolis, USA.
OBJECTIVES: To generate a recombinant fusion protein (FP) based on the
endotoxin-binding domain of bactericidal/permeability-increasing protein
(BPI) and the constant domain of IgG and to test its ability to inhibit
lipopolysaccharide (LPS)-induced macrophage tumor necrosis factor alpha
(TNF-alpha) secretion. DESIGN: A murine macrophage cell line, RAW 264.7,
was transfected with a BPI-IgG FP before incubation with LPS. The amount of
LPS-induced TNF-alpha protein secreted was measured and compared with that
secreted by cells transfected with a control construct. SETTING: Basic
science research laboratory. MAIN OUTCOME MEASURES: Secreted TNF-alpha
protein concentration. RESULTS: After transfection, RAW 264.7-cell FP
expression was detected in cell lysates and supernatants. At each LPS dose
tested, cells transfected with the FP gene secreted less TNF-alpha than did
cells transfected with a control construct. CONCLUSIONS: The FP possesses
substantial antiendotoxin activity, as delineated by inhibition of
LPS-induced TNF-alpha secretion by murine macrophages transfected with the
fusion gene construct. In the future, such FP may be used as a clinical
reagent to reduce the morbidity and mortality associated with serious
gram-negative bacterial infections in surgical patients.
